ME Seminars

The Mechanical Engineering seminar series provides an unparalleled opportunity to an individual to increase the depth of his scientific knowledge. The seminars are held every Friday 5 PM, and also offer an ideal platform to initiate inter-disciplinary work cutting across boundaries.

The department maintains a very vibrant academic atmosphere through various academic initiatives. There is a regular stream of visitors to the department, both for long term and short term, resulting in collaborative research, interactions and seminars. In addition, a number of conferences, workshops and schools have also been organized by the faculty of the department over the years, both at IIT Kanpur, and elsewhere.

Seminars : Monsoon Semester 2017-18

Thu, 24 November 2017 at 5:15 PM

 

Dr. Tanmay Bhandakkar, Department of Mechanical Engineering, IIT Bombay

"Investigation of binder's role on diffusion induced stresses in Lithium-ion batteries"

Abstract:

Lithium (Li) ion batteries are widely being studied due to their high energy and power density. But the electrodes in Li-ion batteries undergo huge volume expansion under constrained conditions causing very high stresses, leading to eventual fracture, loss of electrical connectivity. Binders which are soft, polymeric material surrounding the electrode particle is proposed as a strategy to reduce the stresses -failure in Li-ion battery electrodes. In this talk, the effect of binder on the stresses in electrode will be modeled through a representative system of spherical isolated electrode particle enclosed by binder. Binder will be analyzed for its proportion, stiffness and viscosity under two sets of boundary conditions (i) traction-free and (ii) fully constrained. Finally, current efforts to improve the modeling assumptions will be discussed.

About the speaker:

Dr. Tanmay K. Bhandakkar is an Assistant Professor in the Department of Mechanical Engineering, IIT Bombay.

Thu, 23 November 2017 at 5:15 PM

 

Dr. Pranav Joshi, Experimental Aerodynamics Division, National Aerospace Laboratories, Bangalore

"The effect of pressure gradients on the turbulence in boundary layers"

Abstract:

One of the central questions concerning wall-bounded turbulence is that of its sustenance in a boundary layer. Turbulent boundary layers feature flow structures of a wide range of spatial scales. The small-scale structures close to the wall play an important role in the production of turbulence and are known to be modulated by the large-scale flow structures. I will present the results of a study which utilizes particle image velocimetry (PIV)-based pressure measurements to investigate the role played by pressure gradient fluctuations in this interaction between the large-scale and the small-scale motions. I will also discuss the contrasting effects the mean pressure gradient and the pressure gradient fluctuations have on the turbulence structure.

About the speaker:

Pranav is an experimental fluid dynamicist and works at the Experimental Aerodynamics Division (EAD) of the CSIR-National Aerospace Laboratories in Bangalore. He completed his Ph.D. at the Johns Hopkins University, Baltimore, USA in 2013, working primarily on turbulent boundary layers. After a postdoctoral stint at the Eindhoven University of Technology in Netherlands, where he studied natural convection, he joined EAD in 2016. Currently his work focuses on flow control, specifically on Hybrid Laminar Flow Control (HLFC), which aims to decrease the friction drag on aircrafts by applying boundary layer suction. In his free time, Pranav enjoys singing and reading

Fri, 10 November 2017 at 5:15 PM

 

Prof. Asok Kumar Mallik

"An hour with Leonhard Euler"

Abstract:

Leonhard Euler is one of the all-time greats in mathematics. He is unmatched in quantity, diversity and quality. He continued to publish more than 250 papers over a period of about 50 years after his death. He lost vision in one eye when he was twenty eight years old and was completely blind for the last twelve years of his life. Total loss of vision probably added to his mathematical productivity. He would dictate mathematics to his associates and ask them to go back twenty pages to make a correction. He calculated without any effort just as men breathe as eagles sustain themselves in the air. In this talk, we will present his extraordinary life in a nutshell and discuss only a few of his important results which carry typical Euler’s magic.

About the speaker:

Prof. Asok Kumar Mallik is currently an Honorary Distinguished Professor at Indian Institute of Engineering Science and Technology, Shibpur. He retired as a Professor of Mechanical Engineering at the Indian Institute of Technology Kanpur in 2009. He has held positions at The Institute of Sound and Vibration Research - Southampton, England as a commonwealth scholar and TH Aachen and TU Darmstadt, Germany as an Alexander von Humboldt Fellow. He is a recipient of the Distinguished Teacher Award of IIT Kanpur, Indian National Science Academy Teacher Award and Distinguished Alumnus Award of BESUS (Former Bengal Engineering College, Shibpur). He is an elected fellow of Indian National Academy of Engineering (FNAE), National Academy of Sciences, Allahabad, (FNASc), Indian Academy of Sciences, Bangalore (FASc) and The Indian National Science Academy, New Delhi (FNA) along with being an Institute Fellow at IIT Kanpur. He is an Honorary Fellow of The Association of Mechanisms and Machines for his lifetime contribution in the field of Theory of Mechanisms and Machines. His research area includes Vibration Engineering, Nonlinear Dynamics and Kinematics. He also writes articles and books on Mathematics and Physics at popular level.

Fri, 27 October 2017 at 5:15 PM

 

Dr Satyaki Bhattacharjee

"A manifold based generic reduced order multiscale modelling of complex materials"

Abstract:

Predicting effective material properties of nonlinear heterogeneous complex materials from the knowledge of its microstructure through numerical modeling and computational homogenization (CH) has many applications in engineering design. Direct numerical modeling (DNM) using finite element method (FEM) is capable of predicting material behavior accurately. Unfortunately, DNM and/or CH are computationally expensive methods. To address the computational complexity issue, many researchers have focused on reduced order modeling. However, most of the available schemes are only suited for linear and moderately nonlinear behavior in 2D setting. Moreover, these techniques do not preserve local micro-scale fields in localization processes and cannot accommodate generic loading conditions. Addressing these shortcomings, proposed technique extracts the pattern in the solution manifold, which consists of an ordered set of microscale deformation fields. Each point on the manifold represents data obtained from a detailed parallel finite element simulation of a representative microstructure. In this work, a global dimension reduction technique, Isomap, is used to understand the underlying pattern. Next, a map between the reduced space and the macroscopic loading conditions has been established using a Neural Network. Finally, the microscale deformation field is obtained by exploiting the concept of reproducing kernel Hilbert space (RKHS). Also a novel pattern/physics based sampling strategy has been introduced to construct a representative solution manifold with a few number of simulations. This graph-based technique essentially explores the rotational (principal direction) sensitivity. This novel reduced order model is able to predict the macro-scale as well as micro-scale deformation field for any unknown loading condition without any expensive simulation for finite deformation in 3D setting. Furthermore, this model potentially can accelerate the traditional CH by providing an initial solution vector.

About the speaker:

Satyaki Bhattacharjee has recently finished his PhD in aerospace and mechanical engineering from University of Notre Dame. During his PhD, he has worked on diverse research projects including multi-physics modeling, modeling of complex materials. He has developed manifold based reduced order model, which is a data-driven approach, in the context of complex multi-scale material modeling. Prior to joining PhD program, he obtained a master of technology in aerospace engineering from IIT Kanpur, where he worked on flexible structures. He received his bachelor degree from Bengal Engineering and Science University, Shibpur (Now IIEST, Shibpur) in civil engineering. Satyaki is recipient of several awards including prestigious GE Foundation scholar leader, academic excellence award from IIT Kanpur and Elizabeth Fitzpatrick Graduate Fellowship from University of Notre Dame.

Thu, 26 October 2017 at 5:15 PM

 

Dr Avishek Ranjan

"Inertial waves and helicity in rotating turbulence and in rotating magnetoconvection"

Abstract:

In a rotating fluid, the Coriolis force acts as the restoring force resulting in oscillations known as inertial waves. Columnar flow structures that resemble Taylor columns have been observed in the laboratory experiments of rotating turbulence; however their mechanism of formation is not understood. Using localized turbulence in a periodic box as the initial condition for direct numerical simulation (DNS), the formation of columnar structures is investigated. Helicity, defined as the inner product of velocity and vorticity, is a measure of the degree of knottedness in the flow field. It is well known that inertial waves propagating parallel (anti-parallel) to the rotation axis have negative (positive) helicity. For my doctoral research, I used this helicity segregation characteristic to conclusively show that the columnar structures are actually low-frequency inertial wave-packets. Columnar structures resembling Taylor columns have also been observed in rotating magnetoconvection (dynamo) simulations of the Earth’s core. Moreover, even a similar segregation in helicity, negative (positive) in the north (south) of the equator, has been observed in simulations. Such a segregation pattern can help explain how the magnetic field of the Earth is created and maintained against a natural dissipative decay. What exactly creates such helicity segregation? Could this also be due to inertial waves? These are two very interesting questions that I have investigated during my postdoctoral research, using both periodic box and spherical DNS. Developing new statistical techniques, I have been able to detect a signature of inertial waves in a strongly forced (high Rayleigh number) spherical simulation. Finally, I will talk about my research plan and teaching plan. Using both numerical simulations and experiments, I plan to investigate the magnetohydrodynamic (MHD) flow in liquid metal batteries. These batteries are promising options for grid level energy storage in India and a thorough study is required before the battery size can be scaled for industrial use. I also plan to study the buoyancy-driven flow in rotating compressor cavities, in particular the effect of Coriolis force. Obtaining accurate and reliable heat transfer characteristics is crucial for the aircraft industry both from operational and energy budget considerations.

About the speaker:

Dr. Avishek Ranjan is a postdoctoral research associate in the department of Engineering at the University of Cambridge, presently working on spherical rotating magneto-convection with Professor Peter Davidson. He completed his PhD in the same department in June 2015. To carry out his doctoral work on 'inertial waves in rotating turbulence', he was awarded the Dr Manmohan Singh scholarship by St Johns college, Cambridge. Before his PhD, he completed MS (by research) at IIT Madras when he worked on incylinder optical flow diagnostics under the supervision of Prof Pramod S Mehta and Prof S R Chakravarthy. Along with his MS research at IITM, he also worked as a project associate in a TIFAC-DST sponsored project on ‘the use of straight vegetable oils in engines’ with Prof Mehta. Prior to IITM, he was an assistant manager in the connecting rod & camshaft manufacturing line at Tata Cummins Ltd. Jamshedpur for a year, after completing his B.Tech. (Mechanical engineering) from NIT Jalandhar.

Mon, 23 October 2017 at 5:15 PM

 

Dr. Jayendiran Raja

"Modeling and Experimental characterization of Smart and Polymeric materials applied to Biomedical and Engineering applications"

Abstract:

Smart materials such as shape memory alloys (SMA), piezoceramics, 1-3 piezocomposites etc. are new generation materials surpassing the conventional structural and functional materials. These materials possess adaptive capabilities to external stimuli, such as loads or environment, with inherent intelligence. SMA wrapped with polymeric materials are used as stents in cardiovascular diseases, whereas piezoceramics and 1-3 piezocomposites are used in energy harvesting, underwater and in MRI scans. These materials are characterized under different loading conditions (such as fluid, electrical, mechanical, electromechanical and thermal) to understand their behavior and to be utilized in various applications. Computational modelling will help us to achieve this by means of non-invasive or non-destructive technique.
The developed modelling techniques are validated with experimental measurements, which will provide insight to the design engineers to design and develop these materials for various applications.

About the speaker:

Dr. Jayendiran Raja is a Postdoctoral Researcher at Texas A&M University, Qatar campus. He specializes in computational mechanics applied to material (smart composites, biological soft tissues and
biomaterial) characterization. He holds a PhD in Smart composites material characterization (Indian Institute of Technology Madras, India, 2014), a Masters in Computer Aided Design (Anna University, India, 2007), and a Bachelor in Mechanical Engineering (University of Madras, India, 2001).  He has worked as a Postdoctoral researcher at University of Lorraine-LEMTA-CNRS (Nancy, France) on piezoceramics material characterization .His research interests include Fluid-Structure Interaction of Elastic Shells for Aerospace and Biomedical Applications, constitutive modeling and experimental characterization of piezocomposites for underwater and biomedical applications.

Mon, 09 October 2017 at 2:30 PM

 

Dr. Ravikumar Dumpala

"Engineered CVD Diamond Coated Carbide Tools"

Abstract:

Engineering materials with abrasive constituents (hardness >15 GPa) are difficult-to-cut because the hardness of these constituents is comparable to that of the conventional tools or tool coatings. Diamond is a potential tool material for such applications (hardness ~ 100 GPa). Natural diamond as a cutting tool is discouraged due to its scarcity and cost. However, diamond can be synthesized in the form of coatings using chemical vapour deposition (CVD) method, which is economical. CVD diamond/WC Co is a widely accepted coating/substrate system for tooling applications. But some of the characteristics of diamond such as low thermal expansion coefficient (~ 1.0×10-6K-1), high chemical inertness and high elastic modulus (~ 1050 GPa) proved the vulnerability of this system for high stress cutting applications. In this talk, I will introduce some fundamental aspects and requirements of CVD Diamond/WC-Co system. In particular, substrate material composition, surface pre-treatment, diamond nucleation and crystallinity of the coating will be discussed. In fact, coating substrate adhesion/integrity, hardness and tribological characteristics of the CVD diamond coatings are dependent on their micro/nano grain size. Detailed experimental evaluation of the above characteristics was carried out with respect to the coating grain size. The objective is to develop CVD Diamond/WC-Co system with high interfacial integrity, high hardness and low friction coefficient. To obtain high coating performance, we have successfully developed a novel integrated nano- and micro-crystalline architecture (NCD/transition-layer/MCD) for the diamond coating on WC-Co tools.

About the speaker:

Dr. Ravikumar Dumpala is currently working as an Assistant Professor in the Department of Mechanical Engineering, at VNIT, Nagpur. His expertise is in the area of manufacturing and surface engineering. He received his bachelor’s degree in Mechanical engineering from Andhra University, Visakhapatnam (2004) and M.Tech from NIT Warangal (2007). After 2 years of coding at Tata Consultancy Services (TCS), he moved back to academics. During his PhD (2009-2014) at IIT Madras, he worked on the CVD diamond coatings for the machining of Alm-SiCp metal matrix composites. His current focus is on the development of coatings/ surface composites for aerospace applications especially for the maintenance and repair of metallic components (MRO operations). He is currently funded by DST on “Nickel based composite coatings (Ni-P/hBN) for high temperature tribological applications”. He has several international publications to his credit. He believes in closely working with the industries and research organizations in solving their problems. His vision project is to develop “Cold Spray Technology” for the repair and maintenance of aerospace components, which is the need of the hour. He is a member of Materials Research Society of India (MRSI).

Fri, 06 October 2017 at 5:15 PM

 

Dr. Chiranjit Sarkar

"Lubricating grease flow: A Computational Fluid Dynamics Approach"

Abstract:

Lubricating grease is commonly applied to lubricate parts e.g. rolling bearings, seals and gears. Greases have a complex rheology dominated by its yield stress behaviour, which in turn is a result of the multi-phase composition of the material. The viscosity of the grease is heavily dependent on temperature and shear rate. In a rolling element bearing for instance the shear rate varies from 0.01 to 1e7 1/s, means the viscosity of the grease cover the range from the viscosity of the base oil to an infinite viscosity (solid body). Being able to fully model the flow dynamics of grease, including phase separation, will be highly valuable in the design of lubricated machine elements such as rolling element bearings. Complete models will also be a valuable tool in the process of providing tailor-made greases for different applications. An understanding of the grease flow dynamics enables prediction of grease distribution for optimum lubrication and for the migration of wear- and contaminant particles. In this research work the potential of combined analytical modelling, flow visualizations, and numerical modelling in grease flow dynamics is presented. Specifically, the relation between the rheology of the grease and its impact on the flow motion is of interest in combination with validation of the numerical models in simplified geometries. The numerical models then enable simulations in more complex geometries of particular interest for the grease and bearing industry. It is shown that grease flow is heavily influenced by its non-Newtonian properties and the shear rates in the contact, resulting in distinct regions of yielded and unyielded grease. Further, the numerical models are shown to match well with experiments and analytical models, enabling numerical models on more complicated geometries.

About the speaker:

Dr. Chiranjit Sarkar received his B. Tech degree in Production Engineering from Jadavpur University in 2009, M. Tech degree in Industrial Tribology and Maintenance Engineering from IIT Delhi in 2011 and Ph. D degree in Design of Magnetorheological (MR) Brake from IIT Delhi, India in October, 2014. During his Ph.D program he has synthesized, characterized magnetorheological fluids and fabricated MR brake experimental setup. He has published several journal articles and filed one Indian patent from his PhD work. His post-doctoral research work at Division of Fluid and Experimental Mechanics, Lulea University of Technology, Sweden from January, 2016 to October, 2016 was on Computational Fluid Dynamics of grease flow in channels, bearings and seals. He has recently published work based on grease flow in straight channel, straight channel with restrictions and double restriction seal geometry. He has worked as Assistant Professor at Department of Mechanical Engineering, Delhi Technological University from August, 2014 to June, 2015. He has worked as Assistant Professor at Department of Mechanical Engineering, National Institute of Technology Rourkela from July, 2015 to December, 2015. Currently he is working as Assistant Professor at Department of Mechanical Engineering, IIT Patna.

Wed, 04 October 2017 at 5:15 PM

 

Dr. Rahul Dev

"Performance analysis of modified basin type double slope multi–wick solar still"

Abstract:

This paper presents an outlook to enhance the productivity of a basin type double slope multi–wick solar still by introducing the wicks. The experimental data for different months are presented, and analyzed the effect of climatic and operational parameters on the performance of modified basin type double slope multi–wick solar still (MBDSMWSS). The study has been conducted at Motilal Nehru National Institute of Technology Allahabad (MNNIT Allahabad), Uttar Pradesh (U.P.), India. A significant increase in the heat input, yield, and overall thermal efficiency have been obtained. In the instantaneous efficiency equation, the yield output and the heat input to the solar still is modified as input from both the glass covers and transparent walls are considered for the modified solar still. The result shows that, the maximum yield is obtained as 9012 ml/day (4.50 l/m2 day) for black cotton wick in comparison to 7040 ml/day (3.52 l/m2 day) for the jute wick at 2 cm water depth in MBDSMWSS. Also, for same basin condition, the overall thermal efficiency of MBDSMWSS with the jute and black cotton wicks are 20.94% and 23.03%, respectively.

About the speaker:

Dr. Rahul Dev is an Assistant Professor in Mechanical Engineering Department, Motilal Nehru National Institute of Technology (MNNIT) Allahabad, Allahabad since October 23, 2012. He obtained his B.Tech. in Mechanical Engineering from the Institute of Engineering & Technology, Lucknow in year 2004. He received his Master of Technology degree in Energy Studies from Centre for Energy Studies, Indian Institute of Technology Delhi in year 2007. He also did his Ph.D. in the field of Solar Distillation on topic 'Thermal Modeling and Characteristic Equations for Passive and Active Solar Stills' from Centre for Energy Studies, Indian Institute of Technology Delhi in year 2012. Dr. Dev has supervised several students at MNNIT. His interest are in the field of Solar Energy Applications. He has mainly worked on solar thermal areas such as Solar Distillation, Solar Passive Buildings, Daylighting, Solar Greenhouse Dryers, Solar Water Heating, Solar Air Heater and 'Photovoltaic integrated thermal application'. He has published several papers and has delivered several invited talks. At MNNIT, he teaches Engineering Thermodynamics, Heat & Mass Transfer, Thermal Engineering, Thermo-fluid dynamics, Solar Energy & Its Applications, and Solar Architecture, Non-conventional Energy Sources, Energy Conversion Techniques in UG and PG courses in MNNIT Allahabad.

Sat, 16 September 2017 at 5:00 PM

 

Mr. Nair and Mr. Santhosh

"Method of Machine Building (Conception to Construction – An engineer’s view)"

Abstract:

Presentation overview: Our presentation would cover how we receive challenging problems and how machines are built as solutions. Presentation takes the participants through various stages of machine building. Focus is given on how machines are designed from scratch. Participants would be able to get an understanding on systematic process of design. These stages on conceptualization and designing will be explained through few case studies. Presentation would also cover video clips of few machines built by ETA. Presentation would be followed by a Q&A, where participants can clear their doubts on various aspects of machine building. Take away: We would also throw open a challenge for bright students for innovative design. Students can come out with innovative solutions, which can be shared with ETA within a month. Selected student/team (Maximum 3) will be invited to ETA for presentation and the best design would be given handsome reward.

About the speaker:

About ETA: ETA is a high technology company, providing process solution in different areas of engineering. Some of the typical machines we are manufacturing are high end solid phase welding machines, advanced simulation & testing machines, special purpose machines, metal gathering machines and packaging machines for various applications. ETA Technology is Driven by Innovation and thrives to make environment friendly machines using state of the art technologies.

Fri, 1 September 2017 at 5:15 PM

 

Dr. Rudrodip Majumdar

"Modeling of Flow Patterns of Impurity Aerosol due to Disruption in a Fusion Reactor "

Abstract:

The study focuses on the adiabatic expansion and hyper-velocity acceleration of aerosol impurity in the post-disruption and thermal quench scenario inside the vacuum chamber of a fusion reactor. A pulsed electrothermal plasma (ET) capillary source has been used as a source term simulating the surface ablation of the divertor or other interior critical components of a tokamak fusion reactor under hard disruption-like conditions. The capillary source generates particulates from wall evaporation by depositing transient radiant high heat flux onto the inner liner of the capillary. The particulates form a plasma jet moving towards the capillary exit at high speed and high pressure. Computational work, backed by the data from actual electrothermal source experiments from the in-house facility “PIPE” (Plasma Interactions with Propellants Experiment), shows the supersonic bulk flow patterns for the temperature, density, pressure, bulk velocity and the flow Mach number of the impurity particulates as they get ejected as a highpressure, high-temperature and hyper-velocity jet from the simulated source term. It also indicates the uniform steady-state subsonic expansion of bulk aerosol inside the expansion chamber. Scaling laws in 1-D were developed for the aforesaid bulk plasma parameters for ranges of axial length traversed by the flow, so that one can retrieve the flow parameters at some preferred location. Electrothermal plasmas exhibit highly non-linear nature as a bulk; and thus effect of temperature and the non–linearity of the adiabatic compressibility index on the supersonic flow patterns for high density metal vapor plasma have been presented, where the study shows significant changes in flow parameter values in the extreme limits of suggested nonlinearities. The study brings out finer aspects like agglomeration, recombination and particulate precipitation from the dense bulk plasma as it undergoes isentropic expansion. The analytical expressions to represent the 2-D steady-state spatial evolution of polycarbonate ablated plasma have been also developed and is expected to enable us in predicting the spatial distribution of the debris from the plasma facing components (PFC) or the migrated dust in an efficient manner. The study of dust particulate flow adds to plasma diagnostics database and helps in safe, undeterred operation of the fusion devices.

About the speaker:

Dr. Rudrodip Majumdar was born in Kolkata on 25th day of April in 1987 to his parents Sri Kiriti Majumdar and Smt. Anusri Majumdar. Rudrodip’s school life was divided between Purulia Ramakrishna Mission Vidyapith and Barrackpore Govt. High School. Upon finishing the High School, Rudrodip pursued his B.Tech. degree in Electronics and Communication Engineering from West Bengal University of Technology. During undergraduate studies he developed keen interest in space charge solid state devices and charge carrier transport, following which he pursued computational work in plasma physics and fusion energy at IIT Kanpur in Nuclear Engineering and Tech. Program. Thereafter, Rudrodip joined North Carolina State University in 2011 to pursue his Ph.D. in Nuclear Engineering. His specialization was in studying flow patterns of hyper-velocity electrothermal plasmas. He was awarded Ph.D. in December 2015. He served as a postdoctoral research assistant at NCSU from December 2015 to August 2016. His current stint at IIT Bombay as an institute PDF began in October 2016. Rudrodip is keen about joining a premier academic institute in India for teaching and conducting interdisciplinary research in the fields of high enthalpy flow and clean energy technologies. Apart from academics Rudrodip takes great interest in wildlife conservation, nature photography, creative writing and Indian classical music.

Mon, 28 August 2017 at 4:00 PM

 

Dr. Manish Vasoya

"Fracture Modelling of Heterogeneous Materials "

Abstract:

Predicting roles played by small scale features on the macroscopic response of solids is an important challenge in solid mechanics. The central question is: How can we connect the microstructural parameters of materials to their macroscopic behaviors? In the context of fracture problems, the key issue is that of presence of crack singularity. It makes a sharp interface that governs the relation between the microscopic properties and macroscopic behavior, very sensitive tolocalized small scale phenomena. As a result, a rare specific small scale phenomenon can have a giant effect on the macroscopic failure behavior. The talk presents some results in following two directions (a) brittle failure of heterogeneous materials and (b) toughness of glassy materials. The first direction presents problems of the brittle crack propagation in a heterogeneous toughness field. To this end, some studies on predictingthe effects due to large front deformations will be presented in two cases: half plane crack in a finite body and penny-shape crack in an infinite body. The first case of half-plane crack involves analytical> studies with a verification from experiment. The study shows that the crack front becomes stiff as it deforms. The second case of penny-shape crack focuses on numerical study of arbitrary crack front deformations using numerics. It shows the existence of a fingering instability (crack front becomes more flexible). The second direction of failure of bulk metallic glasses is devoted in understanding the fracture properties of glassy materials. A theoretical model on exploring the notch toughness dependency on the loading rate, notch curvature radius and the history (age) of glass materials will be presented. This theory sheds light on the elementary competition between an intrinsic plastic relaxation time scale and an extrinsic driving time scale, as well as the roles played by nonlinear yielding dynamics and a crossover between thermal and a thermal rheological processes. Non-monotonicity that has been observed in the master function of the notch toughness vs ratio between these two time
scales, is the key feature of the theory.

About the speaker:

My main research interests lie in predicting effects due to small-scale heterogeneities on macroscopic failure properties of materials. Recently, I finished my first postdoc (2015-2017) from the Weizmann Institute of Science, Rehovot, Israel. I worked there in understanding the toughness of glassy materials. I did my PhD from the University of Pierre et Marie Curie (UPMC) - Paris VI. Focus of my thesis was in developing tools to study the brittle crack propagation in a highly heterogeneous medium. I did my master with major in solid mechanics from IIT Delhi. I did master thesis in the field of topology optimization of metal-ceramic composites at the Karlsruhe Institute of Technology, Germany under DAAD/IIT sandwich fellowship. I did my undergraduate in mechanical engineering from the Nirma University, Ahmedabad, India. .

Fri, 25 August 2017 at 5:15 PM

 

Dr. Chandraprakash Chindam

"Multifunctionality, thin-film acoustics, and thermomechanics"

Abstract:

I will talk briefly about my recent research on multifunctional Parylene-C microfibrous thin films. Next, I will outline my future research directions on low-frequency acoustics using thin films, and thermomechanical phenomenon. Following this I will present my teaching interests and abilities. Multifunctionality: Towards sustainable development, multifunctional products have many advantageous over single-function products: reduction in number of parts, raw material, assembly time, and cost involved in a product’s life cycle. As a proof of concept, I will demonstrate the multifunctionalities of Parylene-C microfibrous thin films (µFTFs). As the functionalities of a material are dependent on the microstructure and physical properties, the investigation made was two-fold (1) Experimentally, the wetting, mechanical, and dielectric properties of columnar µFTFs were determined, and correlated to the microstructural and molecular differences between bulk films and µFTFs. (2) Computationally the elastodynamic and electromagnetic filtering capacities of Parylene-C µFTFs were determined. In all cases suitable applications were identified. Thin-film acoustics: The focus of the project is to develop a low-frequency acoustics material. I will present the computational details with initial results and experiments needed for this project. Thermomechanics: A material when subjected to continuous tensile loading, cools in the elastic regime and heats up in the plastic regime. I will aim to understand the thermal behavior of metals and polymers subjected to (1) monotonic tensile loads and (2) shock loads, towards nondestructive evaluation. I will present the work done so far and the future directions.

About the speaker:

Chandraprakash Chindam was born in Hyderabad, India. He received his Bachelors and Masters degrees in Mechanical Engineering at the Indian Institute of Technology Madras (IIT Madras), Chennai, India in May 2010. He was advised by Prof. Krishnamurthy Chitti Venkata (Department of Physics) and Prof. Krishnan Balasubramaniam from 2007 to 2010 in the Center for NonDestructive Evaluation (CNDE), IIT Madras. His Masters thesis he explained the thermomechanical phenomenon, both experimentally and theoretically, in stainless steel SS304 material subjected to cyclic elastic loads and monotonic tensile loads in plastic regime at room temperature. He briefly worked as a Project Officer at CNDE in Summer 2010. After this, he worked in the Noise-Vibration-Harshness Department of Engineering Research Center, Tata Motors Ltd, Pune, India, testing small commercial vehicles on high-speed tracks and in an anechoic chamber. For a year in the Department of Engineering Science and Mechanics, Pennsylvania State University, he studied theoretical microfluidics. Since June 2012, he has researched on Multifunctional Parylene-C microfibrous thin films under the supervision of Prof. Osama O. Awadelkarim and Prof. Akhlesh Lakhtakia. So far, Chandraprakash has co-authored 13 first-author and 2 second-author peer-reviewed journal publications part from conference presentations.

Wed, 23 August 2017 at 2:15 PM

 

Dr. Nikhil Walani Univ Politecnica de Catalunya, Barcelona, Spain

"Mechanics of Biological Membranes"

Abstract:

The function of biological membranes is controlled to a large extent by their interaction with various proteins. A set of these proteins are curved and interact with the membrane by preferentially binding or diffusing to the similarly curved regions of the surface. These proteins are important for many biological processes such as cellular transport and in particular, endocytosis, where the membranes are required to undergo large deformations to engulf the cargo. In the first part of this talk, we focus on the equilibrium of membranes in the presence of three key membrane-deforming proteins, namely, clathrin, BAR and actin filaments. Our study reveals a protein-induced snap-through instability that offsets tension in the membrane and drives transport. In the second part, we focus on the dynamics of protein-membrane interaction. We use Onsager’s variational principle of irreversible thermodynamics to model the sorption (reaction) and diffusion of curvature inducing proteins on a time evolving membrane. The resulting calculations allow us to understand various experimental observations and systematically predict the curvature sensing or generation capabilities of a protein-membrane system depending on a few key physico-chemical parameters.

About the speaker:

Dr. Nikhil Walani is currently a postdoctoral researcher at LaCaN, Barcelona. He did his PhD from University of Houston (Fall 2015) with the thesis focussing on mechanics of cellular transport. Prior to this, he was at IIT Kanpur for the Bachelors in Civil Engineering. He is currently working on modeling chemo-physical interaction of proteins with cell membranes.

Mon, 21 August 2017 at 2:15 PM

 

Dr. Sirshendu Mondal

"Synchronization theory: Describing and suppressing thermoacoustic instability"

Abstract:

Thermoacoustic systems with a turbulent reactive flow, prevalent in fields of power and propulsion, are highly susceptible to oscillatory instabilities. Recent studies showed that such systems transition from combustion noise to thermoacoustic instability through a dynamical state known as intermittency. The aim of this talk is to show the spatiotemporal dynamics during the transition from combustion noise to limit cycle oscillations in a turbulent bluff-body stabilized combustor. The study shows that the aperiodic oscillations during combustion noise are phase asynchronous, while the large amplitude periodic oscillations seen during thermoacoustic instability are phase synchronous. An interesting spatiotemporal pattern is observed during intermittency: patches of synchronized periodic oscillations and desynchronized aperiodic oscillations coexist in the reaction zone. In other words, the emergence of order from disorder happens through a dynamical state wherein regions of order and disorder coexist, resembling a chimera state. Therefore, the dynamics of local heat release rate oscillations change from aperiodic to periodic as they synchronize intermittently. The global synchrony in local heat release rate oscillations is characterized by computing Kuramoto order parameter to quantify the synchronization transition. The temporal variations in global synchrony, estimated through the Kuramoto order parameter, echoes the breathing nature of a chimera state. The talk will also present different states of synchronization between pressure and heat release rate oscillations during quasiperiodic route to chaos in a laminar burner.

About the speaker:

After graduating from Kalyani Govt. Engineering College, Dr. Sirshendu Mondal did his masters and Ph.D. from Jadavpur University, Kolkata. He worked on dynamical transition in pulse combustor analytically and experimentally at JU. He also did a numerical analysis of cold flow and hot flow situations in pulse combustor during his research stay at TU Munich with DAAD sandwich fellowship. Currently, he is pursuing his post-doctoral research at IIT Madras. His current research focuses on the spatiotemporal dynamics during the transition to thermoacoustic instability and exploring different dynamical states using synchronization theory. His research interests include combustion instability, nonlinear dynamics, and time series analysis.

Fri, 18 August 2017 at 5:15 PM

 

Dr. Shiv G. Kapoor

"Development of a Hybrid Process for Manufacturing Surgical-grade Knife Blade Cutting Edges from Bulk Metallic Glass "

Abstract:

The demand for precision surgical knives is enormous. Currently, diamond knives have been the preferred choice among surgeons for use in precision surgeries, owing to the extreme hardness of diamond and the sharpness that can be achieved in single crystal diamond blades, but material and processing costs are high. Bulk metallic glass (BMG) has the potential to be an economically-viable material of similar performance for use in precision surgical knives. To this end, a novel hybrid manufacturing process integrating thermally- assisted micro-molding and micro-drawing has been developed for producing multi-facet and curvilinear surgical-grade knife blade cutting edges from bulk metallic glass (BMG) with edge radii

About the speaker:

Shiv G. Kapoor is a Professor and GrayceWicall Gauthier Chair, Department of Mechanical Science and Engineering University of Illinois at Urbana -Champaign. For nearly 30 years, Professor Kapoor has sustained a relevant and well -supported research program in the areas of manufacturing process modeling and process automation both at the macro - and micro-scale with the goal of developing a science -based understanding of the processes for the purpose of increasing productivity and improving quality. He has directed an NSF-sponsored Industry-University Cooperative Research Center on Machining and Machine Tools for fifteen years. He has published more than 350 technical articles in Journals and conferences of high repute. A Fellow of the American Society of Mechanical Engineers (ASME) and the Society of Manufacturing Engineers (SME), Prof. Kapoor has received numerous ASME and SME society awards including most recent SME Gold Medal in 2015, SME’s most coveted Education Award in 2005 and ASME William T. Ennor Manufacturing Technology Award in 2003. He also received ASME’s Blackall Machine Tool and Gage Awards for outstanding research paper, in 1992, 1997, and 2008. He currently serves as an editor -in-chief for the Journal of Manufacturing Processes and Chair the ASME Technical Committee on Publications and Communications that provide long-range plans and manages affairs of all 30 ASME Transaction and Review Journals for the dissemination of technical knowledge.

Mon, 14 August 2017 at 5:15 PM

 

Dr. Kaustav Chaudhury

"Diffusive Dynamics on Paper Matrix"

Abstract:

From the dawn of modern civilization, writing on a piece of paper with an ink has been one of the preferred modalities of transferring knowledge and information in documented form. On a different note, beginning of this century has witnessed another emerging prospect of paper: acting as the essential building block of a rapid diagnostic kit for testing blood, urine, and saliva samples in ultra-low-cost paradigm. Our study unveils that despite elusively diverse scenarios, there is a uniqueness of liquid spreading through paper, bearing analogy with molecular movement. Scanning electron micrograph of paper reveals distribution of multiple fibers. While each fiber pertains to a channel of micron size diameter, the resultant orientation and distribution of all the fibers corresponds to a randomly distributed network. As a consequence, random motion of the liquid in all possible direction is at occurrence. The complexities in generalizing the underlying physics through a simplified paradigm, constitutes the major challenge. Mapping the single micro-channel behavior onto the random network of fibers, we observe an analogy with the diffusion due to complex migration characteristics of molecules or particles. This culminates in effective diffusive transport behavior on paper, brought about propelling of liquid through the randomly distributed fiber network. Our conceptual paradigm appears to bring in a generalization by providing a simple and consistent accounting of notable applications ranging from liquid imbibitions, mixing and separation, to the hydrodynamics of writing.

About the speaker:

Dr. Kaustav Chaudhury received his PhD in Mechanical Engineering (yr. 2016) from IIT Kharagpur. He completed his MTech in Thermal Science and Engineering (yr. 2011) from the same institute and BE in Mechanical Engineering (yr. 2009) from Jadavpur University. Focusing on fundamental fluid mechanics and its implications in cutting edge technological applications, Dr. Chaudhury has published in journals of international repute, including Applied Physics Letters, Physical Review E, Langmuir, Lab on Chip etc. One of his research works “Diffusive Dynamics on Paper Matrix” has received an overwhelming appreciation and published as news articles in Phys.org, Science Daily, The Economic Times and Business Standard. One of his collaborative works “Swirling Flow Hydrodynamics in Hydrocyclone” (published in Industrial & Engineering Chemistry Research of ACS Publications) receives appreciation and has been conferred with Industrial Institute of Mineral Engineers (IIME) best paper award on beneficiation. Presently Dr. Chaudhury is working in Schlumberger, Pune, India as Modeling and Simulation Engineer in the area of fluid mechanics. Here he has delivered projects focusing on new product development and issues faced in the fields. His work on mixing tank, has been selected for Asia Level Reservoir Symposium 2017, and presented satisfactorily.

Fri, 4 August 2017 at 5:15 PM

 

Dr. Arindam Das

"Designing Solid and Liquid-Impregnated Surface for Ultra Low Adhesion of Clathrate Hydrate "

Abstract:

Clathrate hydrate is a solid ice like material which forms when some hydrophobic guest molecules stabilize cell structures made of hydrogen bonded water molecules. Methane hydrate, a type of clathrate hydrate forms inside oil and gas pipes at higher pressure above the freezing point, may cause severe problem in flow assurance and even catastrophic accident by plugging. Cyclopentane clathrate hydrate, which forms similarly at water-oil hydrophobic interface at atmospheric pressure, was used as a model system for safe experimental study on hydrate adhesion. Both theoretical and experimental studies were carried out to design and fabricate surfaces with a non aqueous liquid barrier film which is expected to minimize the hydrate adhesion. Liquid impregnated surface (LIS) is one of such surfaces with a thermodynamically stable impregnated lubricating liquid phase inside its texture. Detailed thermodynamic design map of LIS inside two immiscible liquid phase environment was constructed based on the interfacial energetics. Subsequently silicon based LIS were constructed from surfaces of well ordered texture and appropriate chemistry, produced by standard lithography and reactive ion etching. Adhesion forces between these surfaces and clathrate hydrate were measured using a custom made device based on the cantilever deflection. Some of these surfaces showed extremely low or zero hydrate adhesion and accumulation. Surfaces of ultra low hydrate adhesion based on industrial material and process were also developed.

About the speaker:

Arindam Das is currently working as a postdoc researcher in Mechanical Engineering department of the Massachusetts Institute of Technology. His present research topic is clathrate hydrate adhesion on solid surfaces. He received his Doctorate degree in Mechanical Engineering from the University of Illinois at Chicago in 2013. His doctorate research was on multifunctional polymer-nanoparticle composite surfaces of extreme wettability. He received his Bachelor of Mechanical Engineering degree from Jadavpur University in 2006.

Wed, 2 August 2017 at 2:15 PM

 

Prof. Amitabha Ghosh

"Professor Hatwal, National Emergency and the Discovery of Chaos in Mechanical Systems"

Abstract:

The talk is aimed at bringing to the audience how bad things lead to good endings in the field of science. A few past famous examples will be presented to show how some unfortunate happenings lead to some major breakthroughs in science. The discovery of the occurrence of chaotic motion in mechanical systems was first noticed at IIT Kanpur and the first experiment on mechanical chaos was conducted here. The audience will be told what circumstances lead to this discovery which were induced by some very unfortunate happenings in our country. The talk is not a technical lecture but a story of the department in mid seventies.

About the speaker:

Amitabha Ghosh received his Bachelor of Engineering and Master of Engineering degrees from Bengal Engineering College, Shibpur, (Calcutta University) and Doctorate degree from Calcutta University in 1969. He was a former faculty at the Mechanical Engineering department, IIT Kanpur, and from 1997 to 2002 he served IIT Kharagpur as the Director. Currently he is a Platinum Jubilee Senior Scientist of the National Academy of Sciences, India, Allahabad and also an Honorary Distinguished Professor at Bengal Engineering & Science University, Shibpur. His research and academic interests are in Basic Mechanics, Kinematics and Dynamics, Advanced Manufacturing and Robotics. His books are considered classics and are followed extensively in India and abroad. He has received many awards including Prof Jai Krishna award from the Indian National Academy of Engineering, Doctor of Science (h.c.) from Bengal Engineering and Science University, Shibpur and was the first to receive the Distinguished Teacher award form IIT Kanpur. He is a Fellow of the Institution of Engineers (India), Indian National Academy of Engineering, New Delhi, Indian Academy of Sciences, Bangalore, Indian National Science Academy, New Delhi and the National Academy of Sciences, India, Allahabad.

Mon, 31 July 2017 at 2:15 PM

 

Dr. Soham Mujumdar, University of Illinois at Urbana-Champaign, USA

"High-performance and Sustainable Manufacturing via Process Modeling"

Abstract:

Demand for techniques capable of micro-scale machining has been increasing rapidly as the trend towards miniaturization continues. Micro electrical discharge machining (micro-EDM) process has been successfully employed in aerospace, automobile, and other industries due to its unique capabilities of manufacturing high-accuracy micro-parts with a range of materials irrespective of their hardness. However, one of the major disadvantages of the micro-EDM process is its low productivity, mainly due to the low energy efficiency of individual discharges and accumulation of debris particles in the inter-electrode gaps, especially, while drilling holes, milling 2D/3D cavities and machining micro-scale features. This research presentation will describe the development of a multi-physics model to gain fundamental knowledge of the micro-EDM process and to explore possible mechanisms of productivity improvements. The modeling tools developed in this research enable an understanding of the micro-EDM plasma and material removal mechanism at the workpiece. The presentation will also overview development of atomized dielectric-based EDM process based on the understanding of the process mechanisms obtained through modeling of the conventional EDM process. Use of atomized dielectric in EDM as a novel solution both to reduce the consumption of dielectric and to efficiently flush out the debris and therefore, can be a sustainable alternative to the conventional EDM process. Atomized dielectric-based EDM process that involves supplying the dielectric in the form of atomized droplets that coalesce on impacting the workpiece surface to form a thin, moving film, which can penetrate the inter-electrode gap. The presence of a thin film of the dielectric can confine the plasma expansion during an EDM discharge, thereby, focusing the discharge energy in a narrow region. Moreover, moving dielectric in the gap could lead to a faster restoration of the dielectric strength and enhanced heat removal from electrode surfaces at the end of each discharge when compared to the stationary dielectric, thereby, providing stable discharge conditions for the subsequent discharges. The final part of the presentation will briefly discuss the application of the liquid atomization technology for cutting fluid delivery in titanium machining. This research aims to study the effect of various atomization-based cutting fluid delivery (ACF) system parameters on the film formation and associated film characteristics in order to improve the effectiveness of the ACF system in titanium machining. Viewing the research program in its entirety, its most consequential impact will be the creation of a scientific and technological base for development of high-performance and sustainable alternatives to the existing manufacturing processes.

About the speaker:

Soham Mujumdar is a Postdoctoral Research Associate at Micromanufacturing Processes Research Lab at University of Illinois at Urbana-Champaign. He received a B. Tech degree in Production and Industrial Engineering from the Indian Institute of Technology Roorkee in 2009 and Ph.D. in Mechanical Engineering from the University of Illinois at Urbana-Champaign in 2016. Dr. Mujumdar’s research interests include development of micro/meso-scale manufacturing processes, sustainable manufacturing. His Ph.D. dissertation research involved development of a multi-physics model of electrical discharge machining (EDM) process to study the process of dielectric breakdown, formation and expansion of EDM plasma, and resulting material removal mechanism. His current research involves study of atomization-spray-based cutting fluid delivery (ACF) system for titanium machining, development and modeling of atomized dielectric-based EDM process, and virtually-guided certification of die cast manufacturing processes.

Tue, 11 July 2017 at 5:15 PM

 

Dr. Cemil Alkan Gaziosmanpaşa University, Turkey

" State of The Art of Thermal Energy Storage Materials"

Abstract:

Thermal energy storage (TES) is known as the most efficient among energy storage means. Due to the promising potentials, scientists are keen on improving innovative materials and validating systems. Material development and processing could be two different issues in this respect but overlapping in some cases may be synergistic. Materials could be designed according to processing necessity, efficiency or economy. The phase change materials (PCMs) which are the most popular in TES science have been improved very effectively in the last two decades. For genuine usages they should still be further improved. The present proposed sophisticated means to exploit PCMs are composites, solid-solid PCMs and microencapsulated PCMs. GOUPAL is an experienced laboratory developing innovative TES materials from Tokat city of Turkey.

About the speaker:

Prof Dr Cemil Alkan is chemist from Gaziosmanpaşa University in Tokat city of Turkey with a PhD degree on polymer science and technology. He has mainly concentrated on polymer based TES materials in the last 15 years. He produced 85% encapsulation ratio in composites of PCMs with engineering thermoplastics, microencapsulated PCMs at competitive diameters and original solid-solid polymeric PCMs in the past. In one of the last projects he incorporated to a consortium (EU-India Project) to overcome encapsulation of salt hydrates in polymeric matrices to produce passive TES systems. The task is very important because salt hydrates have never been proposed as TES material for passive systems.

Tue., May 30, 2017, Time: 5:00 PM, Venue: FB 370

 

Dr. Indrasen Singh, IIT Indore

"Cavitation induced fracture in brittle metallic glasses"

Abstract:

Metallic glasses (MGs), which are metals solidified in an amorphous state, have shown attractive mechanical properties such as high strength, yield strain and good corrosion resistance. They exhibit heterogeneous plastic flow by formation of shear bands (SBs) at temperatures well below the glass transition temperature. However, they can be very brittle with KIc ∼ 1 - 15 MPa m1/2 or very tough (KIc ∼ 80 MPa m1/2 ). Experiments and MD simulations suggest that failure in the brittle MGs occurs by cavitation with little shear banding and can be traced to nanoscale fluctuations in atomic density. To explain this behaviour, we propose a model of a heterogeneous solid containing a distribution of weak zones to represent a brittle MG. In this talk, I will discuss the plane strain finite element simulations of cavitation in such an elastic-plastic solid subjected to biaxial loading. We have examined the effects of the yield strength and volume fraction of the weak zone as well as the stress state on the cavitation response. It is found that the presence of weak zones can dramatically lower the cavitation stress, and also gives rise to interesting cavitation bifurcation behaviours including the possibility of snap cavitation. We have also conducted continuum simulations of crack initiation in a heterogeneous plastic solid under mode-I plane strain, small scale yielding conditions. Results show that a three-step process is involved in the catastrophic fracture observed in brittle MGs.

About the speaker:

Dr. Indrasen Singh received B.Tech degree in mechanical engineering from NIT, Allahabad in 2004. Subsequently, he joined the position of scientist at ARDE, Pune, a premier lab of DRDO. In 2010, he moved to PTC software (india) Pvt. Ltd., Pune and worked there for 3 years as a software developer. He obtained his PhD from IISc, Bangalore. His PhD work focused on understanding the fracture and deformation response of metallic glasses and nanoglasses. In Oct, 2016, he joined post-doctoral position at NUS, Singapore. Since April 2017, he is working as assistant professor at IIT, Indore.

Fri., April 07, 2017, Time: 5:00 PM, Venue: FB 370

 

Dr. Mirza Faisal Baig Mechanical Engineering, AMU

"Turbulent drag reduction using thermal buoyancy as active control"

Abstract:

The talk involves study pertaining to Direct Numerical Simulations (DNS) of a turbulent channel flow subject to spatially modulated thermal forcing with a special interest to realize reduction of skin-friction drag. Thermal forcing has been employed using both streamwise and transverse arrays of heated strips on the bottom wall of the channel. The simulations have been carried out for a fixed friction Reynolds number Reτ =180 with friction Richardson number Riτ varying from 15 to 30.The periodic transverse strips exhibited an increase in skin-friction drag with a decrease in the width of hot strips though wider hot strips exhibit a slight decrease in skin-friction drag. Streamwise periodic strips exhibited a reduction in skin-friction drag of the order of 8% with an increasing trend in reduction of friction drag with increasing Riτ. The mechanism responsible for turbulent skin-friction drag reduction due to streamwise thermal forcing affects two processes, namely: (a) Advection of streamwise kinetic energy from the buffer-layer to outer layer by the wall-normal buoyancy forces leading to formation of border low-speed streaks over the heated regions and it (b) brings about suppression of cross-flow fluctuating velocities which in turn weakens the transient growth of the turbulent streaks.

About the speaker:

Dr. Mirza Faisal Baig is professor at Mechanical Engineering, AMU. He obtained Batchelors in Mechanical Engineering from AMU, Aligarh, Masters in Aeronautical Engineering from Canada and PhD from University of Southampton, UK. His research work is related to fundamental aspects of near-wall turbulence, flow control methodologies in both compressible and incompressible turbulence, Geophysical flows, Planetary dynamo modeling.

Fri., Mar. 31, 2017, Time: 5:00 PM, Venue: FB 370

 

Dr. Kaustubh Kulkarni Materials Science and Engineering, IITK

"Investigations of Interdiffusion in Multicomponent Solids"

Abstract:

Diffusion in solids controls many metallurgical processes including various phase transformations, homogenization and joining of materials. Control of interdiffusion is also crucial aspect of material systems that operate at elevated temperatures as they may experience degradation in performance due to alloy loss or change of microstructure caused by interdiffusion of various alloying elements during service. Most of the applications are based on multicomponent systems containing three or more components. However, there is a severe lack of data on diffusion in multicomponent solids. A brief theoretical background on multicomponent diffusion will be presented at the beginning of this talk followed by experimental methodologies used to determine interdiffusion coefficients in the multicomponent systems. Experimental interdiffusion studies carried out in various practically important systems will be presented including the binary Al-Mg, ternary Ti-Al-Mo and quaternary Fe-Ni- Co-Cr systems. Diffusional interactions or the effect of one diffusing species on the diffusion of the others is an important aspect of multicomponent diffusion. Its manifestation in the form of uphill diffusion and zero flux planes will be highlighted. Use of the interdiffusion data in practical applications will be illustrated with couple of examples of alloy and processes being developed in our research group.

About the speaker:

Dr. Kaustubh Kulkarni is a faculty in the department of Materials Science and Engineering at IITK. He completed his B.E. in Metallurgical Engineering from College of Engineering Pune and his PhD in Materials Engineering from Purdue University, USA. Before joining IITK in 2012, he worked in Automotive Research Association of India, Pune and with GM R&D Bangalore. Dr. Kulkarni has 19 journal publications and 2 US patents.

Wed., Mar. 29, 2017, Time: 5:00 PM, Venue: FB 370

 

Prof. Roger Sauer Aachen Institute for Advanced Study in Computational Engineering Science, RWTH-Aachen, Germany

"On the computational modeling of cell membranes using isogeometric shell elements"

Abstract:

The presentation discusses the computational modeling of lipid bilayer membranes based on the nonlinear theory of thin shells. Several computational challenges are identified and various theoretical and computational ingredients are proposed in order to counter them. In particular, C1-continous, NURBS-based, LBB-conforming surface finite element discretizations are discussed. The constitutive behavior of the bilayer is based on in-plane viscosity and (near) area-incompressibility combined with the Helfrich bending model. Various shear stabilization techniques are proposed for quasi-static computations. All ingredients are formulated in the curvilinear coordinate system characterizing general surface parametrizations. The consistent linearization of the formulation is presented, and several numerical examples are shown.

About the speaker:

Prof. Dr. Roger A. Sauer (Roger) is currently engaged with RWTH-Aachen as an Associate Professor with the AICES (Aachen Institute for Advanced Study in Computational Engineering Science). His research interests are catered towards Nonlinear continuum mechanics, advanced finite element and multi-scale methods, contact and adhesion mechanics, membrane and shell theories, self-cleaning surface mechanisms, biological cell membranes and multi-physics of interfaces. He earned his Bachelors degree in Civil Engineering in 2002 from the University of Karlsruhe, Germany and Masters and Doctoral degrees in 2003/2006 from the University of California, Berkeley, USA. Before joining RWTH-Aachen in 2008 as a Junior Research and Group Leader, Roger did his habilitation with Prof. Peter Wriggers. Roger has received notable recognition for his research and teaching contributions till date. Hs is a recipient of the J. Tinsley Oden fellowship (2016), member of the ‘Junges Kolleg’ of the North-Rhine-Westphalian Academy of Sciences and Arts (2012), member of the Emmy-Noether program of the German research society (DFG, 2009), participant of the Academy of Excellence ‘Computational Material Science’ (2008), recipient of the Robert L. Taylor FEAP (2004) and Earle C. Anthony (2003) fellowships, and many more. He is a member of many societies, e.g., Biophysical Society, Euromech to name a few, and is collaborating actively with close to 20 researchers around the world. Roger has been very successful in garnering third party research funds (net: ~2355, 000 €). Roger is a co-author in 47 Journal articles, 104 peer reviewed Conference articles and 5 Book chapters. He has delivered numerous invited talks in the USA, UK, India and Germany, has co-organised many conferences and mini-symposia. Roger is in the Editorial Board of the Journal of Micromechanics and Molecular Physics and the Journal of Adhesion, has advised many Doctoral and Post-Doc researchers, masters and undergraduate students.

Friday, Mar. 10, 2017, Time: 5:00 PM, Venue: FB 370

 

Dr. Siva Vanapalli Dept. of Chemical Engineering, Texas Tech University, USA

"Understanding the Hydrodynamics of Drops in Microfluidic Networks for High Throughput Biological Analysis "

Abstract:

Droplet-based microfluidics where reactants or biological species are encapsulated in thousands of tiny water droplets is witnessing a tremendous interest for applications in chemistry, biology, medicine and material science. To enable the development of robust droplet-based devices, my laboratory has been investigating the dynamics of confined drops in a special class of fluidic networks called microfluidic parking networks. These networks consist of a repeated sequence of loops, with each loop containing a fluidic trap to park drops. In this talk, I will discuss how we harness collective hydrodynamics of drops to engineer multi-functional microfluidic devices. I will also present some counterintuitive fluid phenomena associated with squeezing and coalescence of parked drops; and highlight the underlying hydrodynamic mechanisms. Finally, I will discuss our efforts to translate these inexpensive microfluidic platforms for high throughput analysis in biology and medicine.

About the speaker:

Dr. Siva Vanapalli is an Associate Professor in Chemical Engineering at Texas Tech University. He obtained his B.Tech from IIT Kharagpur and Ph.D. from the University of Michigan. He is currently the holder of the Bill Sanderson and the Ed & Linda Whitracre Faculty Fellowships at Texas Tech. His research interests are in the areas of microfluidics, complex fluids, cancer, healthy aging and technology development. He received the CAREER Award from the National Science Foundation and the Rising Star Award from the Cell & Molecular Bioengineering Group of Biomedical Engineering Society. He has developed several enabling microfluidic technologies, which led to six pending patents, two of which have been licensed to start-up companies. To date he has mentored 8 Postdoctoral researchers, 14 PhD students, 38 undergraduate students and 3 high school students.

Monday, Feb. 27, 2017, Time: 5:00 PM, Venue: FB 370

 

K. Velusamy Indira Gandhi Centre for Atomic Research, Kalpakkam

"Challenges in Thermal Hydraulic Design of Sodium Cooled Fast Reactors "

Abstract:

Indian nuclear power programme has been envisaged to have three stages for judicious utilization of limited uranium and vast thorium resources. In the second stage, sodium cooled fast breeder reactors (FBR) are deployed. Design of a fast breeder reactor demands detailed knowledge of thermal hydraulic parameters prevailing in the reactor at various conditions, prediction of which poses interesting challenges. Sodium, being a liquid metal has a high heat transfer coefficient and hence is the natural choice as the primary coolant to remove very high heat fluxes (~2 MW/m2) encountered in the compact reactor core. Another favourable factor for selection of sodium is its high boiling point (880C) which leads to low pressure systems. Thus, the main loads on FBR structures are of thermal origin, viz., high operating temperature (creep), large temperature gradient (thermal stress) and large number of cyclic variations in temperature (thermal fatigue) due to various incidents taking place in the plant. In FBR system, the Biot number is of the order of unity, demanding multi-physics heat transfer studies for accurate prediction of structural temperatures. Wide operating temperature range coupled with a high volumetric expansion coefficient of sodium is favourable for natural convection heat removal. However, a large buoyancy force in sodium pools leads to high Richardson number ~1, posing the risk of thermal stratification and the associated temperature fluctuations and thermal fatigue in the structures. Sodium jets from fuel bundles at differing temperatures entering into a common reactor pool leads to high-cycle thermal fatigue as a consequence of jet instabilities and large heat transfer coefficient of sodium. Nuclear heat is generated in fuel pin bundles with helical wire spacers housed inside a hexagonal wrapper. All the sub-channels of the bundle are not of identical hydraulic resistance, which leads to flow mal-distributions and circumferential temperature variations in fuel clad. Knowledge clad hotspot temperature is essential for safety analysis. During emergency decay heat removal conditions, there is favourable interaction between pool and inter-wrapper sodium which transports considerable fraction of core decay heat to the pool limiting the clad temperatures, especially during the onset of natural convection. Prediction of this phenomenon calls for multi-scale modelling of the entire primary system. The main drawback of sodium is its violent chemical reaction with air and water. Hence, inert argon gas is maintained above sodium free surfaces to avoid sodium-air contact. Large free surface velocity in compact reactor pool leads to argon gas entrainment in sodium and the associated risk reactivity fluctuations in the core, which is a serious safety issue. As a part of reactor safety analysis, it is essential to assess the effectiveness of online monitoring of core cooling. During a postulated complete flow blockage in fuel bundle, the entire scenario, viz., the rate of damage to the subassembly, radial propagation of damage in the core, the number of subassemblies that are likely to get damaged during such an accident, relocation of the molten fuel from core to core catcher and effective cooling of the core debris by safety grade decay heat removal system by natural convection need to be established. This calls for a coupled multi-phase and multi-physics thermal hydraulic studies coupled with appropriate validation exercises. The full paper would address thermal hydraulic issues specific to sodium cooled fast reactors, computational models developed to understand them, typical case studies.

About the speaker:

Dr. K. Velusamy is working as Outstanding Scientist and Associate Director, Nuclear Systems Analysis Group, in Indira Gandhi Centre for Atomic Research, Kalpakkam. He is also a Senior Professor in Homi Bhabha National Institute, Mumbai. He is a specialist in Computational Fluid Dynamics & Fast Reactor Thermal Hydraulics. He completed his B.E. (Honours) in Mech. Engg. from Madras Univesity in the year 1983, his M.Tech (Mech. Engg). from IIT-Kanpur in 1985 and his PhD from IIT-Madras in 2000. He, a member of Indian Nuclear Society & Indian Society for Heat and Mass Transfer. He an Editorial Board member of Annals of Nuclear Energy. He is Fellow, Indian National Academy of Engineering. He got DAE - Scientific and Technical Excellence Award for the year – 2006, HBNI Distinguished Faculty Award for the year – 2015 and DAE Group Achievement Awards for Design of PFBR Components – 11 times. He has published 102 Journal papers and 125 Conference papers. He has guided 16 PhD Theses and 27 M.Tech / M.S theses.

Friday, Feb. 10, 2017, Time: 5:00 PM, Venue: FB 370

 

Ankit Jain University of Toronto, Canada

"Thermal and optoelectronic properties of semiconductors and metals from atomistic simulations "

Abstract:

Thermal Transport: With miniaturization in size, thermal transport is becoming increasingly important in the design and realization of micro-electronic devices. Due to additional scattering of heat carriers at boundaries, the thermal conductivity of material is reduced in these devices. While the reduced thermal conductivity deteriorates device performance and could result in device failure for applications such as microprocessors, it is advantageous for thermoelectric energy conversion, where the figure of merit is inversely proportional to the thermal conductivity. Our objective is to understand and predict the thermal transport physics in technologically important materials by using first-principles based density functional theory calculations and the Boltzmann transport equation. We consider phonon-phonon scattering in semiconductors and phonon-phonon and phonon-electron scattering in metals. The scattering rates are obtained using the Fermi golden rule. We study the phonon thermal transport properties in (i) Conventional semiconductors such as silicon and germanium, (ii) Semiconductor nanostructures (silicon nano-porous lms) (iii) Two-dimensional semiconductor (phosphorene), and (iv) Metals (aluminum and gold). Our predicted values of thermal conductivities show excellent agreement with the experimentally measured values (wherever available) without the use of any fitting parameters and highlights the phonon thermal transport physics in these technologically relevant materials. Optoelectronic Properties: The optoelectronic properties determine material's performance in photovoltaic and light-emission applications. The photoluminescence quantum yield is inversely affected bynon-radiative losses. Similarly, defects can trap the charge carriers and deteriorate the device performance in photovoltaic applications. Our objective is to use atomistic simulations to study non-radiative losses in colloidal quantum dots (CQDs) for light-emitting applications. In particular, we use density functional theory fitted tight-binding Hamiltonian to study Auger and trap-assisted non-radiative losses in CQDs. Our calculations explain the experimental findings and help in the design of improved CQDs with suppressed non-radiative losses.

Friday, Feb. 03, 2017, Time: 5:00 PM, Venue: FB 370

 

Dr. Debasis Chakraborty Technology Director of Computational Dynamics Directorate, Defence Research and Development Laboratory, Hyderabad

"CFD applications in Aeropropulsive design of missiles "

Abstract:

Over the last few decades, CFD has developed into a rich and diverse subject and is emerged as a major component of applied and basic fluid dynamic research alongwith theoretical and experimental studies. Simultaneous development of new computers, numerical algorithms, physical and chemical models of flow are responsible for the great impact of CFD in both basic and applied scientific/engineering problems. Presently, CFD methods are employed routinely for the estimation of various complex aerodynamic and propulsion flow parameters where experimental data cannot be obtained economically or feasibly and contributing significantly in reducing developmental cost and time for aerospace vehicle design. In India, the designers of missiles are depending heavily on CFD techniques for the accurate prediction of various aerodynamic and propulsion parameters in the design exercise. DRDL has developed a host of indigenous grid generators, 3-dimensional Euler, RANS and LES solvers using advanced numerical techniques and physical models and are routinely used to estimate various aerodynamic parameters pertaining to DRDO missile systems. Systematic validations were carried out through comparisons against reliable experimental results to assess their accuracy and application range. Aerodynamic characterization of various missiles in complete M- - δ-φ flight regime, store separation from aircraft, heat shield separation of hypersonic vehicles etc., are some of the notable applications of these codes. Commercial RANS codes are effectively applied for design and analysis of many advanced propulsion systems including hypersonic air breathing mission, scramjet combustor, Integrated rocket ramjet intake, jet vane, base flow etc. Key performance parameters were predicted and propulsion systems were optimized through the analysis of various thermochemical parameters obtained from numerous numerical simulations. An indigenous Large Eddy Simulation (LES) code is developed to predict compressible turbulence. Central differencing (Maccormack scheme) and upwind (modified SLAU2) scheme are coupled together to treat the smooth flow as well as the flow with discontinuity. Gibbs phenomena sensor and digital filtering are implemented to detecting shocks and contact discontinuity and to provide inflow turbulence. An alternate upwind scheme namely Rotated HLL (RHLL) scheme is also developed to enhance the applicability of the code. The scheme is validated extensively for number stringent canonical problems namely, supersonic flow past forward facing step (Emery test case), supersonic flow past compression corner, hypersonic flow past cylinder, stationary compressible isentropic vortex, lid driven flow in a square cavity, Toro’s blast wave problem, shock-vortex interaction problem, subsonic and supersonic backward facing step problems, supersonic mixing layers etc. The code is currently being tested for practical engineering problems like shock-boundary layer interaction, intake unstarting, sonic injection in supersonic cross flows etc. The lecture will contain two parts. In the first part, a brief overview of the development and application of CFD techniques for aero-propulsive characterization of various DRDO missile systems will be presented. The development and validation of the indigenous compressible LES code will be deliberated in the second part of the lecture.

About the speaker:

Dr. Debasis Chakraborty is currently working as Technology Director of Computational Dynamics Directorate at DRDL Hyderabad. Prior to that he worked in Vikram Sarabhai Space Center during 1986-2001. He received M.Sc in Applied Mathematics from Jadavpur University, M.Tech in Computational Mechanics from IIT, Kharagpur and Ph.D in Aerospace Engineering from IISc, Bangalore. He was AICTE-INAE Distinguished Visiting Professor in Aerospace Engineering at IISc Bangalore during 2007 – 2009. Currently he is also a visiting professor at Center for Modeling, Simulation and Design (CMSD), University of Hyderabad. He is a Fellow of INAE, Aeronautical Society of India, and Institution of Engineers. His works have been awarded with many awards like, DRDO Scientist of the year award 2012, DRDO award for Best innovation/futuristic Development, 2010, Technology Group award (Group leader) of DRDL for 2008. He is the member of aerodynamics and propulsion panels of AR&DB and expert panel member of National Supercomputing Mission. His research interest includes CFD, Aerodynamics, Propulsion, Turbulence and Combustion modeling, Transient and unsteady flows, Numerical methods. He has published more than 215 research papers in various international journals and conferences in the area of CFD.

Friday, Jan. 20, 2017, Time: 5:00 PM, Venue: FB 370

 

Dr. Om Pal Singh NETP/ME, IIT Kanpur

"Uncertainty evaluation of reliability of shutdown system of a medium size fast breeder reactor"

Abstract:

The Shutdown System (SDS) of a typical Medium Size Fast Breeder Reactor (MSFBR) is a safety system designed to shut down the reactor on demand. This is one of the most important and critical system from safety point of view and therefore failure probability of this system is normally kept less than 1.0 x 10−6 per reactor year. This target is achieved by introducing redundancy, diversity and reducing the common cause failure (CCF) among the components/subsystems of SDS and is confirmed by the Reliability Analysis performed using Fault Tree (FT) analysis. It is well known that there are uncertainties in the values of the failure rate of the components of SDS. Therefore, uncertainty analysis has been carried out to assess the uncertainty in the failure rate of SDS due to uncertainty in failure rates of its components. It is observed that the spread in the failure rate of the SDS is less than the spread in the failure rate of the individual components of SDS. Sensitivity analysis carried out for failure rate of control and safety rods indicate that an increase of a factor of 10 in the failure rate of components of SDS increases the failure rate of SDS by factor of 2 only. The results of the analysis are of practical importance and provide insight in the propagation of uncertainty in the failure rate of SDS components on the failure rates of SDS. In the proposed presentation, the details of the features of MSFBR and its shutdown systems, the methodology used in carrying out the reliability and uncertainty analysis and the results will be presented.

About the speaker:

Dr. Om Pal Singh is Ph.D. in Physics from Indian Institute of Technology (IIT), Delhi. He served as Secretary of Atomic Energy Regulatory Board (AERB) and Director of one of its division for about 7 years and was involved in regulatory and safety aspects of Indian nuclear and radiation facilities, matters relating to HRD/RTI/Vigilence /Internatinal relations, interface between media and AERB. He carried out R&D on space and time dependent safety analysis of Pressurized Water Reactors (PWRs) and design aspects of loose neutronic coupling in large size PWRs. Before joining AERB, he served Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam for 31 years in different capacities including as Head Reactor Physics Division. He is an Expert in Reactor Physics and Deterministic & Probabilistic Safety Analysis of nuclear reactors. He is recognized by Madras and Bombay university as Ph. D. Guide. He guided 7 Ph.D thesis in IGCAR Kalpakkam. He has to his credit over 60 research papers in refereed journals, more than 100 papers presented in conferences and about 200 design and analysis reports on Indian Fast Reactors. He served as member in the Steering committee of International Atomic Energy Agency (IAEA) on HRD in member states with nuclear power plants. He provided the IAEA Expert Services several times in Indonesia. He has been Chief Investigator in 3 IAEA`s Coordinated Research Projects. He is also an holder of Alexander Von Humboldt Foundation fellowship. He visited TAMU, College Station USA and University of Michigan, Ann Arbor, USA for a short period in 2013 as a visiting scientist. He joined IIT Kanpur as visiting professor in the first week of August 2010 and served for 9 semesters. He guided 8 M.Tech theses on topics such as dynamic simulation of high temperature gas cooled reactors, conceptual studies on CANDLE reactors and uncertainty analysis of safety systems (Decay heat removal and shutdown systems) of fast reactors. Today`s presentation is on one of the studies carried out by one of the M.Tech. students on reliability and uncertainty analysis Shutdown System of Indian PFBR that is under construction in Kalpakkam. He has keen interest in quality of education of students in schools. He was secretary and vice president of 'KG Association' in Kalpakkam for 4 years and served for 2 years as Chairman of `Managing Committee` of Department of Atomic Energy's six high schools and one inter college at Anushaktinagar in Mumbai. For school students, his slogan is 'learning without knowing that one is learning'.

Friday, Jan. 13, 2017, Time: 5:00 PM, Venue: FB 370

 

Dr. Sanjay Khattri Western Norway University of Applied Sciences, Norway

"Optimization of fire emergency systems through computational fluid dynamicse"

Abstract:

Longitudinal ambient air ventilation is the most common methodology for maintaining amicable environment during normal situations while providing an evacuation path during tunnel fire emergencies. The present work investigates the influence of forced ventilation air oxygen concentrations on the tunnel fire dynamics. Mixing ambient air with inert gasses such as nitrogen, argon, carbon dioxide will change the oxygen concentration of ambient air. To quantify the influence of the oxygen content on the critical tunnel safety parameters, we perform multiple computational fluid dynamics simulations on a reduce size tunnel while preserving the Froude number. We develop analytical expressions to estimate the importance of oxygen content on tunnel fire dynamics. By employing the Froude scaling technique, we extrapolate these relations to the realistic tunnels. Furthermore, for the ambient air ventilation, the comparison of these expressions to the experimental data display good agreement. We find that by adjusting the oxygen concentration, we can control the parameters such as the maximum tunnel ceiling temperature, the fire growth rate, the maximum heat flux to the tunnel floor, the maximum flux on the tunnel ceiling and maximum heat release rate. It can help evacuation and assist in fire-fighting. The work shows that we can control the tunnel fire severity by adjusting oxygen concentrations to levels significantly improving tunnel fire safety.

About the speaker:

Dr. Sanjay Khattri is working as a professor at the Western Norway University of Applied Sciences. He holds a bachelor degree, a master degree and a Ph.D. degree from IIT - BHU, Texas A & M College Station and the University of Bergen, respectively. He has worked within the oil industries for more than four years and within the academic institutes for more than fourteen years. His research interests include scientific computing, computational fluid dynamics, and applications of these for solving real life problems. Presently he is working with fire dynamics in confined environments such as subsea and road tunnels.

Friday, Jan. 6, 2017, Time: 5:00 PM, Venue: FB 370

 

Dr. Srihari Dodla Department of Mechanical Engineering, National Institute of Technology, Calicut

"Flow Behavior and Texture Evolution of a Lamellar Copper-Silver Composite"

Abstract:

In the last 20 years, big afford has been made to optimize conductor materials for magnet technology such as Cu-Ag composites. Two-phase eutectic (lamellar) Cu-Ag composites consist of alternative finely spaced layers of Cu-rich and Ag-rich lamellae. In this contribution, we study the microstructure and texture evolution in near-eutectic cold drawn Cu-Ag composites using a combination of X-ray diffraction (XRD) and finite element simulations with an implemented crystal plasticity model 1,2 . Stress strain curves from compression tests and measured XRD texture data before and after the compression are presented 3 . Lamellar textured Cu-Ag polycrystals are modelled by periodic Voronoi tessellations in the finite element software ABAQUS. The numerical calculations use periodic boundary conditions to simulate the mechanical behavior of textured polycrystals, considering Voce-type hardening behaviour and initial texture. The numerical model is validated by experimental compression tests for a constant strain rate 10 -4 s -1 at room temperature. The numerical results in terms of the texture of each phase and the mechanical behavior have been compared with the experimental results.

About the speaker:

Dr. Srihari Dodla received the B. Tech. degree in Mechanical Engineering from the Sri Venkateswara University, Tirupati, in 2009, the M. Tech degree in Applied Mechanics from the Indian Institute of Technology, Madras, in 2011, and the Ph.D. degree in Institute of Mechanics from Otto von Guericke University Magdeburg, Germany, in 2015. He worked as a research assistant in Institute of Materials and Joining Technology at Otto-von-Guericke University Magdeburg, Germany during Aug 2014 to May 2015. From July 2015 to Nov 2016, he was a PDRA in the Wolfson school at Loughborough University, UK. In December 2016, he joined the Ad-hoc faculty of the department of Mechanical Engineering of the National Institute of Technology Calicut, India. His fields of interest are crystal plasticity based on isomorphism, multiscale material modelling, texture evolution, homogenization methods (FEM, Taylor, VPSC) and texture components.

Wednesday, Nov. 30, 2016, Time: 10:00 AM, Venue: FB 370

 

Professor Chris Manzie Department of Mechanical Engineering, University of Melbourne, Australia

"Optimal design of controlled aerodynamic systems"

Abstract:

The overall design of aerodynamic systems has many interacting components to consider, from the structural geometry of the hardware to the computational platforms and eventually the controller architecture and gains. The traditional development cycles typically involve hardware iterations followed sequentially by controller development, leading to the potential for more design iterations than necessary or over-specification of the components within the final complete system. Advances in simulation capability potentially enable the use of optimization techniques within the design process to address these potential issues, ideally leading to better overall designs and shorter development cycles. However, evaluation of performance at each design point for a dynamic system may involve lengthy computation times, thus the overall optimization becomes non-trivial and necessitate the use of targeted approaches. In this talk I will (attempt to) briefly discuss three problems in this regard: global optimization of structural design parameters in the aerodynamic system; locally optimal co-design of structural and controller parameters; and optimal design of model based controllers in aerodynamic systems.

About the speaker:

Chris Manzie is a Professor in the Department of Mechanical Engineering at The University of Melbourne. He is also an Assistant Dean (Research Training) and the Mechatronics Discipline coordinator in the Melbourne School of Engineering. His research interests are in model-based and model-free control and optimisation, with applications in a range of autonomous systems related to energy, transportation and mechatronics. Currently, he is an Associate Editor for Elsevier Control Engineering Practice; IEEE/ASME Transactions on Mechatronics; IEEE Transactions on Control Systems Technology and Elsevier Mechatronics.

Friday, Nov. 04, 2016, Time: 5:00 PM, Venue: FB 370

 

Dr. Raghunandan Sharma, Department of Mechanical Engineering, IIT Kanpur

" Development of carbon nanomaterials based cathode catalyst layers for polymer electrolyte membrane fuel cells"

Abstract:

Carbon nanostructures are of utmost importance in nanoscience and nanotechnology in view of their promising physical, mechanical and electrical properties. Properties such as high electronic conductivity, high corrosion resistance and large surface area of carbon nanotubes (CNT) and carbon nanofibers (CNF) make them the materials of choice for catalyst layers in polymer electrolyte membrane fuel cells (PEMFCs). As large-scale application of PEMFCs is restricted by their high initial cost attributed mainly to the Pt-based catalyst layers used to catalyze oxygen reduction reaction (ORR) at cathode, alternative Pt-free catalysts based on heteroatom doped carbon nanomaterials are of significant interest. However, despite numerous Pt-free ORR catalysts being investigated, their catalytic activity remains low as compared to that of Pt-based ones. As a part of the present research work, cost efficient PEMFC cathode catalyst based on Pt-nanoparticle coated CNTs has been developed. Further, heteroatom doped carbon nanostructures synthesized by chemical vapor deposition (CVD) have been investigated for their suitability as Pt-free ORR catalysts. The seminar will focus on the effects of various process parameters on the ORR activity of CNT supported Pt-based electrocatalysts. Next, the synthesis of Pt-free, doped carbon-based electrocatalysts through CVD will be discussed. Nature of ORR active sites will be deliberated in light of the ORR activity-structural correlations.

About the speaker:

Dr. Raghunandan Sharma is a postdoctoral fellow at Department of Mechanical Engineering, IIT Kanpur since February-2016, after completion of his PhD in Materials Science from the Materials Science Programme, IIT Kanpur. He completed his masters (MSc) from Department of Physics, University of Rajasthan in 2005 and moved to Physical Research Laboratory Ahmedabad for a short project thereafter. Later, he did his MTech from the Materials Science Programme, IIT Kanpur in 2009 and continued to work as a PhD student. His current research interests include the development of materials for electrochemical power conversion and storage devices. His areas of focus include Pt-free cathode electrocatalysts for PEMFCs and electrode materials for Li-ion batteries.

Wednesday, Oct. 19, 2016, Time: 5:00 PM, Venue: FB 370

 

Dr. Mahesh Manchakattil Department of Mechanical & Aerospace Engineering, IIT Hyderabad

"Coupled structural-acoustic response of an elastic plate to sound waves in a duct"

Abstract:

The designing, developing and testing of skin panels that can withstand severe unsteady pressure loads is a serious challenge faced by the aerospace industry. One of the problems faced by the panels is acoustic fatigue which can cause structural damages and can reduce the service life of aircrafts significantly. The dynamic and multiphysics nature of the problem makes its analysis, prediction and testing even more difficult. Results for the coupled response of a duct-mounted, elastic plate to acoustic loading using a modal expansion of the relevant eigenmodes exist in the literature. The effect of uniform grazing flow on the coupled response is investigated. As an effort to reduce the amplitude of the plate's response, the effect of constraining an interior point on the plate is explored in this study. This modification can alter the amplitude and spectral characteristics of the plate's response. Interestingly, some new peaks are observed in the response because of the excitation of unsymmetric modes which are otherwise dormant. The results of the ongoing investigation of the forced vibration of a clamped-free beam using the large displacement beam equation will be presented. The equation is solved by expanding the beam displacement using a series of modes which are the Eigenfunctions satisfying the linear beam equation along with the boundary conditions for a clamped-free beam. The forced vibration due to uniform external pressure having harmonic time dependence is calculated for various values of forcing frequency.

About the speaker:

Dr. Mahesh Manchakattil is an Assistant Professor in the Department of Mechanical & Aerospace Engineering at IIT Hyderabad. Prior to that he was working in Defence Institute of Advanced Technology, Pune since 2013. He received his B.Tech and M.Tech degrees in Aerospace Engineering from IIT Madras in 2004. From 2004 till 2007, he worked as scientist/engineer in the Aerodynamics R & D division of Vikram Sarabhai Space Centre, ISRO. He received his Ph.D. in aerospace engineering from University of Illinois, Urbana-Champaign in 2013. His research interests include Aeroelasticity, Computational Mechanics, Warhead Mechanics and Aeroacoustics. He has worked on the structural- acoustic coupled response of aircraft panels, aeroelastic analysis of composite and delta wings. He is also interested in the numerical algorithms for Multiphysics simulations. In collaboration with Armament R&D Establishment, Pune, he is investigating explosive-metal interaction for design of shape charge warheads against concrete targets. He has seven publications on these topics in international journals.

Friday, Sept. 30, 2016, Time: 5:00 PM, Venue: FB 370

 

Dr. Debopam Das Department of Aerospace Engineering, IIT Kanpur

"Generation of clean vortex ring and its axial interaction with a cylinder"

Abstract:

In this talk I will discuss about a novel method for generating vortex rings that circumvent some of the drawbacks associated with existing methods in producing them. The predominant effects that occur in previously used methods are due to presence of some of the other vortices such as, stopping vortex, piston vortex, image vortex and orifice lip generated vortices in the early stage of development. These disturbances influence the geometric, kinematic and dynamic characteristics of a vortex ring and lead to mismatches with classical theoretical predictions. It is shown in the present study that the disturbance free vortex rings produced, follow the classical theory. Flow visualization and PIV experiments are carried out in the Reynolds number (defined as ratio of circulation (Γ) and kinematic viscosity (ᵥ)) range, 2270< ReΓ <6790, to find the translational velocity, total and core circulation, core diameter, ring diameter and bubble diameter. In reference to the earlier studies, significant differences are noted in the variations of the vortex ring diameter and core diameter. A model for core diameter during formation stage is proposed. The translational velocity variation with time shows that the second order accurate formula derived using Hamilton's equation by Fraenkel (Jl Fluid Mech. 1972, 51, pg 119-135) predicts it best. Subsequently the axial interaction of this classical vortex ring with a thin circular cylinder has been studied. It is observed that due to the presence of the cylinder, there is an increase in the velocity of the vortex ring. Also, noticeable changes in the characteristic properties of vortex ring such as core circulation, core diameter and ring diameter have been observed. To justify these experimental observations quantitatively, an analytical study of the interaction under inviscid assumption is performed. The inviscid analysis does predict the increase in velocity during the interaction, but fails to predict the values observed in present experiments. However, when the theory is used to correct the velocity change through incorporation of the effects of axisymmetric induced boundary layer region over the cylinder, modelled as an annular vortex sheet of varying strength, the changes in the translational velocities of vortex rings match closely with the experimental values.

About the speaker:

Dr. Debopam Das is a professor of the Department of Aerospace Engineering, IIT Kanpur, India. His research interest is in flapping flight, incompressible and compressible vortex rings, instability and transition of unsteady internal flows and instability of buoyant and non-buoyant free shear flows

Friday, Sept. 23, 2016, Time: 5:00 PM, Venue: FB 370

 

Dr. Subhanker Paul Department of Mechanical Engineering, IIT Kanpur

"Reduced Order Model for Nonlinear Stability Analysis of Two-Phase Flow Channel"

Abstract:

Stability analysis of two-phase flow systems are of preponderant interest to the researchers for several decades. Analysis of such systems like Boiling Water Reactors (BWRs) are carried out using large scale system codes. Due to extensive computational effort associated with the system codes, they are less capable of investigating the nonlinear behavior of the system. In contrast, Reduced Order Models (ROMs) prove itself as an important tool, through which deeper insights of instability phenomena (Density Wave Oscillations, DWOs) can be obtained with a few simplified representative system equations. The prime objective of the research is development of ROMs to carry nonlinear stability analysis of a two-phase flow system. As a part of the work, improved thermal hydraulic ROMs using homogeneous equilibrium and drift flux correlations are developed; including a new insight of density variation of subcooled coolant in single phase region. It is noted that the density variation of the coolant due to heating in the single phase region is significant. The aforementioned variation is captured by considering the density to be a function of local enthalpy along the length of the channel. Time dependent spatially linear approximations are considered for single phase enthalpy and two-phase quality and nonlinear coupled ODEs are obtained by weighted residual approach. Linear stability analysis is carried out using the model and stability maps are shown in various parameter planes namely phase-change number (Npch), subcooling number (Nsub) and applied external pressure drop (∆Pext). The occurrences of subcritical and supercritical Hopf bifurcations across the stability boundaries are shown for various sets of design parameters. In subsequent studies, a Nodalized Reduced Order Model (NROM) is developed, where discretization is done by equally dividing the enthalpy interval provided by inlet subcooling in the single phase region. Adopting the moving boundary scheme, coupled nonlinear ODEs are obtained for consecutive intervals. The unique feature of the developed NROM is that, it behaves as an auto-adaptive scheme where the mesh sizes vary according to the enthalpy variation in the flow system. This reduces the computational effort drastically for non-uniform axial enthalpy variation. In addition to this, the NROM is developed with internalization of different two-phase friction factor multipliers which helps to predict the pressure drop more accurately compared to existing ROMs. Using the NROM, the DWOs are analyzed for non-uniform axial heat flux shapes; considering single humped and double humped heat flux profiles. It is seen that, the bifurcation characteristics of the above said system changes significantly as the heat flux is changed from uniform to non-uniform even though the total heat flux remains same. In addition to these, the ROMs developed in the previous section are coupled with point reactor kinetics to investigate the instability phenomena of a BWR and AHWR.

About the speaker:

Dr. Subhanker Paul is an Institute Post Doctoral Fellow (IPDF) in the Department of Mechanical Engineering at IIT Kanpur. He has joined in Feb 2016. He completed his graduation in physics (hons) from Ranchi University in 2010. After this he did his masters (M.Sc) on Energy science from IIT Bombay in 2012. He earned Ph.D from IIT Bombay in 2015. His research interests include stability of dynamical systems, and two-phase flow instability with an application to different nuclear reactor systems. During his Ph.D he worked with Prof. Suneet Singh on development of Reduced Order Models which can be used as a tool carry stability analyses of Density-Wave-Oscillations in a two-phase flow system. Presently he is working on nuclear coupled thermal hydraulic instability analyses of Boiling Water Reactors and Advanced Heavy Water Reactors.

Wednesday, Sept. 21, 2016, Time: 5:00 PM, Venue: FB 370

 

Dr. Abhijit Sathe, GIBBS, Mumbai

"Open-loop Geothermal Cooling for Commercial Air Conditioning Systems "

Abstract:

Geothermal power is a form of renewable energy that makes use of near-constant temperature of the earth and groundwater. Open-loop geothermal cooling or heating involves using the groundwater as a heat sink or source. Groundwater is extracted from bore wells and heat is exchanged with it using a heat exchanger. The hotter or cooler water (depending on cooling or heating mode) is sent back to the ground where it mixes with the groundwater table and dissipates heat to the Earth. Geothermal cooling for a commercial air-conditioning is investigated in detail. Groundwater temperature is seen to be 7-8 degrees below ambient during peak summer months. Compared with an IKW/TR of 1.5 for air-cooled chillers and 0.8 for water-cooled chillers equipped with cooling towers, geothermal cooling provides an IKW/TR of 0.55. This results in energy savings of approximately 40% and 10% over air-cooled and water-cooled chillers, respectively in addition to a 100% saving on water and chemicals. Drawbacks and future prospects of open-loop geothermal cooling are discussed.

About the speaker:

Dr. Abhijit Sathe is a Mechanical Engineering professional. Abhijit received his Bachelor degree in Mechanical Engineering from Shivaji University in 1999, M.Tech from IIT Madras in 2001 and PhD from Purdue University in 2008. He worked as a Vice President – Technology and Engineering at GIBSS in Mumbai from December 2015 to May 2016, as a Senior R&D Engineer at Parker Hannifin from June 2008 to November 2015 and as a Steam Turbine design Engineer at BHEL Hyderabad from September 2001 to August 2004. Abhijit’s core competencies are thermodynamics, heat transfer, refrigeration and air conditioning, renewable energy and liquid cooling. He has written several journal papers and conference proceedings and also has a few United States patents to his name.

Friday, Sept. 09, 2016, Time: 5:00 PM, Venue: FB 370

 

Dr. Samarjeet Chanda,Institute Postdoctoral Fellow, Dept. of Mechanical Engineering, IITKanpur

"Simultaneous Estimation of Principle Thermal Conductivities of Layered Honeycomb Composites "

Abstract:

Composite materials, find extensive use in many engineering applications such as structural components of spacecrafts and satellites because of their superior mechanical properties. Knowledge of their thermal properties like effective directional thermal conductivity is important from the viewpoint of design of components involving such materials. This study primarily aims at the development of an experimental methodology to simultaneously estimate the principal thermal conductivities and thermal contact conductance of anisotropic composite medium using an inverse technique. Principal thermal conductivities of anisotropic media are treated as unknown parameters and are estimated by solving an inverse heat conduction problem. The methodology involves three major parts namely the forward problem, measurements, and the inverse solution. The forward problem involves the heat conduction equation in a three dimensional domain subjected to boundary conditions as realized in experiments. A synergistic combination of Artificial Neural Networks and Genetic Algorithms is used to solve the inverse problem along with experimental data. Simultaneous estimation of all the three principal thermal conductivities and thermal contact conductance is thus enabled from a single experiment.

About the speaker:

Dr. Samarjeet Chanda is a Post Doctoral Fellow in the Department of Mechanical Engineering, IIT Kanpur, since March 2016. He received his B.E in Mechanical Engineering from R.V. College of Engineering (Visvesvaraya Technological University), Bangalore and after working for a brief period of one year as a design engineer for coal based thermal power plant with GMR Energy Limited, he joined IIT Madras for his higher studies. He completed his MS/PhD from IIT Madras in December 2015. His doctoral dissertation focused on simultaneous estimation of principal thermal conductivities of layered honeycomb composites using inverse methodology. His doctoral work was based on a collaboration between IIT Madras and ISRO Bangalore. His research interests include transport property estimation using inverse techniques, design of appropriate instrumentation for carrying out measurements in vacuum environment and inverse problem solutions using evolutionary techniques like Genetic Algorithms. He is presently estimating thermal and mass diffusivities of a solute-solvent system from interferometric data.

Saturday, Sept. 03, 2016, Time: 12:00 PM, Venue: FB 370

 

Dr. Arshad Afzal,Dept. of Mechanical Engineering, Yonsei University,South Korea

"Numerical Analysis and Optimization of Thermal-Fluid systems using Surrogate-based Optimization Techniques"

Abstract:

Improvement in heat and mass transfer characteristics and controlling pressure losses is important to develop high performance systems for wide variety of thermal-fluid applications viz. Turbomachinery, Turbine blade cooling, Microchannel heat-Sinks, Micromixers, among others. Optimization techniques are now recognized as a promising tool in the design of modern heat and mass transfer equipment and processes. Design optimization based on computational fluid dynamics (CFD) analysis has become a reliable tool for heat and mass transfer applications due to the rapid increase in computing power. Accurate, high-fidelity CFD simulations are used to design efficient systems that meet desired performance requirements. Unfortunately, high fidelity simulations are often computationally expensive and impractical for the entire design process. To alleviate this problem, surrogate models have been used to reduce the computational burden with a reliable representation of the simulation data. Surrogate based optimization has been used by many researchers to develop efficient designs for a wide range of applications, especially in the thermo-fluid field, where the analysis using Navier-Stokes equations is quite time-consuming. The development of an efficient thermal-fluid system relies on the underlying physics of the flow, and the potential to fully exploit it. However, lack of understanding may result in inefficient and sub-optimal designs. Thus, a series of steps viz. development of novel designs, parameterization with design and manufacturing constraints and optimization is required for a successful design. To build a surrogate model, a high number of runs from the simulation model may be required to ensure an acceptable accuracy. However, design of experiments (DOEs) procedures can be used to economically construct a surrogate with fewer runs of the original simulation model. A number of DOEs method have been used by researchers to select the design sites for the simulation model, namely full factorial, fractional factorial, central composite design (CCD), Latin hypercube sampling (LHS) etc. Upon a careful review of the literature, it was found that the tentative surrogate always depends on the number and distribution of sample points. Therefore, it is important to study the effect of number and distribution of sample points in the design space with the available surrogate models. With recent developments in surrogate-based optimization and their application to engineering problems, evaluation of comparative performances of surrogate models in light of available DOE procedures is desired. The research aims to resolve two distinctive issues under consideration. Firstly, the research will lead to substantial advancement and development of thermal-fluid systems which are efficient and effective. A combination of numerical and experimental approaches will be used to determine the optimal design. Secondly, it will provide useful insights on the effective use of surrogate-based optimization techniques. The outcomes of research will provide a clear perspective to practitioners and designers on the application of surrogate modeling based optimization properly with respect to DOE procedures (sample size and distribution, adaptive sampling) as well as choice of appropriate surrogate model.

About the speaker:

Dr. Arshad Afzal is Brain Korea 21 (BK 21) Post-Doctoral Fellow in the Department of Mechanical Engineering at Yonsei University, South Korea. He has completed his PhD Degree (Thermal and Fluids Engineering) from Inha University, South Korea in 2015. He received his M. Tech (Thermal Engineering) and B. Tech (Mechanical Engineering) degrees from Aligarh Muslim University in 2009 and 2006, respectively. His research interests are Microfluidics, Computational Fluid Dynamics, Gas Turbine cooling and Thermal/ Fluids Design Optimization. He has published research papers on these topics in reputed International Journals and conferences (For details, please refer to https://www.researchgate.net/profile/Arshad_Afzal). Currently, he is working on the design of internal cooling systems for gas turbine applications using numerical simulations and Naphthalene Sublimation Technique for experiments. Recently, he has received the INSPIRE Faculty award from Department of Science and Technology (DST), Government of India.

Friday, Sept. 02, 2016, Time: 5:00 PM, Venue: FB 370

 

Lt Col Dr. Tushar P Ghate, Government of India

"Nuclear Energy Overview"

Abstract:

Aim of the presentation is to give an overview on the basics of the nuclear technology, nuclear reactors and development of nuclear technology in Indian context. The topic covers an introduction to the nuclear technology since its inception and various milestones achieved thereafter over decades. The viability of nuclear power has been underlined with statistics referred from various national and international facilities. Front end and backend of nuclear power generation process has also been covered in brief. Various types of nuclear reactor technologies have been brought out with suitable examples. Indian nuclear facilities have also been covered in the subject. Indo-US nuclear deal was an important landmark towards fulfillment of India’s quest for power in 21th century. Background and its implications have also been covered in the presentation. The topic concludes with briefs on use of nuclear technology in development of nuclear weapons.

About the speaker:

Dr. Tushar P. Ghate holds PhD in Nuclear Energy with his thesis entitled Nuclear Energy: Changing Dynamics and Feasibility Analysis of Siting at Nuclear Power Plant at xyz Location in India. This study was aimed at analyzing the current technologies, laws, provisions and guidelines necessary for setting up nuclear power plant in India and to bring out framework for the setting up of nuclear power plants in future, considering all current and proposed legal and technological developments/amendments in Indian context. Having worked in the Government/defence sector for last 20 years, he has undertaken multifarious independent academic and executive assignments. He has headed trial and evaluation department in Military Engineering College and conducted trials and evaluations of various radiation detection equipment introduced in India. He was also involved in carrying out analysis of Indo-US civil nuclear deal and its futuristic implications on power generation perspective in India vis-a-vis opportunities in Indian contexts. He has written papers on various aspects of nuclear energy, terrorism, forensic and security in national and international journals.

Friday, Aug. 12, 2016, Time: 5:00 PM, Venue: FB 370

 

Dr. Mahesh Sucheendran Department of Aerospace Engineering, Defence Institute of Advanced technology, Pune

"Coupled Structural-Acoustic Analysis of a Point-constrained Plate in a Duct"

Abstract:

The designing, developing and testing of skin panels that can withstand severe unsteady pressure loads is a serious challenge faced by the aerospace industry. One of the problems faced by the panels is acoustic fatigue which can cause structural damages and can reduce the service life of aircrafts significantly. The dynamic and multiphysics nature of the problem makes its analysis, prediction and testing even more difficult. Results for the coupled response of a duct-mounted, elastic plate to acoustic loading using a modal expansion of the relevant eigenmodes exist in the literature. As an effort to reduce the amplitude of the plate's response, the effect of constraining an interior point on the plate is explored in this study. This modification can alter the amplitude and spectral characteristics of the plate's response. Interestingly, some new peaks are observed in the response because of the excitation of unsymmetric modes which are otherwise dormant.Furthermore, the frequency response by varying the point constraint location is also analyzed. Mode-localization phenomenon, which is the localization of vibration in specific regions of the plate, is observed for selected constrained points.

About the speaker:

Dr. Mahesh Sucheendran is an Assistant Professor in the Department of Aerospace Engineering at Defence Institute of Advanced technology, Pune since 2013. He received his B.Tech and M.Tech degrees in Aerospace Engineering from IIT Madras in 2004. From 2004 till 2007, he worked as scientist/engineer in the Aerodynamics R & D division of Vikram Sarabhai Space Centre, ISRO.He received his Ph.D. in aerospace engineering from University of Illinois, Urbana-Champaign in 2013.His research interests include Aeroelasticity, Computational Mechanics, Warhead Mechanics and Aeroacoustics. He has worked on the structural-acoustic coupled response of aircraft panels, aeroelastic analysis of composite and delta wings. He is also interested in the numerical algorithms for Multiphysics simulations. In collaboration with Armament R&D Establishment, Pune, he is investigating explosive-metal interaction for design of shape charge warheads against concrete targets. He has seven publications on these topics in international journals.

Friday, July 22, 2016, Time: 5:00 PM, Venue: FB 370

 

Dr. Xiaoliang Jin, School of Mechanical and Aerospace Engineering , Oklahoma State University, USA

"Mechanics, Dynamics and Material Behavior in Precision Machining Processes"

Abstract:

Precision and micro machining are widely used in the manufacturing processes for optics, biomedicine, aerospace and electronics areas. Process efficiency and components quality highly depend on the fundamental mechanisms of material deformation and surface generation in the precision machining processes. This seminar presents the current research progress in Dr. Jin’s group, including the following topics: 1. Mechanics and dynamics in micro machining of metallic materials with tool edge geometry. A generalized analytical model based on material plasticity is proposed to predict the stress distribution and cutting force with round tool edge effect. Chatter stability of micro machining with process damping due to tool edge-surface contact is predicted and validated. 2. Machinability in micro machining of typical amorphous materials including bulk metallic glass and BK-7 glass. The mechanism in machining amorphous materials is different from that on metallic materials due to their unique microstructure and mechanical properties. Experimental investigations on the effect of process parameters on the crystallization of zirconium based bulk metallic glass in micro milling are conducted. A 2-D vibration stage is developed to apply vibration assisted milling in machining brittle glass in ductile mode. 3. Prediction of coupled torsional-axial vibration of drilling tool. Vibration assisted drilling has been applied in composites, high-strength alloys and bone materials for various applications. The coupled axial-torsional vibration of drilling tool plays a significant role in the drilling performance. An efficient analytical dynamic model is developed to predict the drill dynamics considering the clamping boundary conditions.

About the speaker:

Dr. Xiaoliang Jin is an Assistant Professor in the School of Mechanical and Aerospace Engineering at Oklahoma State University, USA. He received Bachelor and Master degrees in Mechanical Engineering from Beihang University in China, and obtained PhD degree in Mechanical Engineering from the University of British Columbia, Canada, in 2012. His research interests include precision manufacturing, mechanics and dynamics of precision machining processes, vibration assisted machining of brittle materials, surface texturing and controller design for precision machine tools. He has published papers in the ASME Journal of Manufacturing Science and Engineering, CIRP Annals – Manufacturing Technology, Journal of Materials Processing Technology etc. He has been leading several national and state research projects in US. He is an awardee of the Faculty Early Career Development (CAREER) Program from the National Science Foundation, and an awardee of 2016 Outstanding Early Career Researcher from Oklahoma State University.

Monday, May 23, 2016, Time: 3:00 PM, Venue: FB 370

 

Dr. Mohammed Istafaul Haque Ansari, JNCASR Bangalore

"Patterns and Segregation in Vertically Vibrated Granular Matter"

Abstract:

This research explores the dynamical behavior of granular materials via experiments in a vertically vibrated granular bed. Experiments are designed with the primary objective to understand the pattern formation dynamics that manifests in a vertically-vibrated container filled with mono-disperse spherical particles as well as binary mixtures of equal sized spherical particles of different materials. We report, for the first time, (i) a variety of “phase-coexisting” patterns having different spatial and temporal order, a novel “Ratcheting/ Oscillatory” cluster, and the related phase diagrams in vibrated binary mixtures, (ii) a novel unsteady dynamics of the so-called “density-inverted” Leidenfrost state and (iii) the micro- structural signatures of the transition from the “bouncing-bed” to the Leidenfrost state. The phase coexisting patterns are segregation-driven and exhibit in mixtures with large density- contrasts wherein a gas-like phase can coexist with a liquid-like phase separated along the horizontal direction – this type of ‘horizontal’ segregation, induced along the length of the container in the horizontal direction, was never reported in the literature on vertically vibrated granular mixtures. We also discovered a simple recipe to control convection patterns by adding a small amount of heavier (or lighter) particles in an otherwise monodisperse system. With this technique, one can control the number of convection rolls emerging in the system and can transit from a convection- state to a “partial” convection state (i.e. the convection rolls coexisting with a Leidenfrost State along the horizontal direction) and subsequently to a “complete” Leidenfrost State and vice versa.

Thursday, Apr 28, 2016, Time: 4:00 PM, Venue: FB 370

 

Dr. Jaya Mukerjee, Head, Isotopic Cleanup Process and Engineering Section, Laser & Plasma Technology Division Bhabha Atomic Research Centre, Mumbai

"Laser in Nuclear Fuel Cycle: Challenges and Technology Development Necessity for Thorium Fuel Cycle"

About the speaker:

Dr. Jaya Mukherjee is a senior Scientist and Head of Isotopic Clean up Process Physics & Engineering Section in Bhabha Atomic Research Centre, Mumbai. She has worked in design, development and implementation of sub-systems for laser based purification processes for technology demonstration. Currently, she is leading a team for demonstration of laser based purification process, involving multidisciplinary expertise. Her specializations include Characterization of Free Jet expansion of atomic metal vapour, Simulation of Free jet using indigenously developed direct simulation code in parallel form, working on complete solution for control and operation of the process, Design and development of vapour generator system, Study of condensation and flow of liquid metal in hot environment, Design of liquid metal corrosion resistant coating, development of non-interfering on-line measurement systems for process parameters, etc. She has received DAE Scientific & Technical Excellence Award and Group Award for her contributions to the department.

Thursday, Apr 14, 2016, Time: 4:00 PM, Venue: FB 370

 

Dr. Man Prakash Gupta, Post Doctoral Fellow, Department of Mechanical Engineering, Georgia Institute of Technology, Atlanta, USA

"Electrical and Thermal Transport in Nanotube/Nanowire Based Thin-film Composites and Devices"

Abstract:

Some of the most critical challenges of modern civilization are related to energy conversion, consumption and dissipation. Nanomaterials based composites and devices can play an important role in finding the innovative solutions to these challenges. In the present talk, I will talk about the charge and heat transport in the emerging composites and devices based on the nanomaterials such as carbon nanotubes (CNTs), Silver nanowires (AgNWs) and Graphene. In particular, I will discuss two applications: thin-film transistors (TFTs) and transparent conducting electrodes (TCEs) which will enable flexible, transparent and energy-efficient integrated circuits, solar cells, e-displays, implantable medical devices and chemical, bio- and optical sensors.

CNTs are known for their exceptional electrical, thermal, mechanical, optical, and chemical properties; and CNT network based TFTs are
considered to be very promising candidate for the building blocks of future flexible macro-electronics. CNTs in CNT-TFTs are deposited on low
thermal conductivity substrates, which can impede the heat dissipation from Joule heating resulting in high temperature. Excessive self-heating in the device can degrade their electrical and thermal performance and could potentially lead to failure of the devices. In order to understand and mitigate self-heating issues in CNT-TFTs, we develop and employ a computational framework based on the physics of electron transport, thermal transport and heterogeneous percolation theory. The model is used to study how device parameters such as the channel geometry (length and width), network morphology (network density, CNT length and alignment distribution, CNT junction topology), and interfacial thermal resistances affect the heat dissipation and the high-field breakdown of CNT- TFTs. The findings provide useful design guidelines to enhance the performance of CNT-TFTs for macro and flexible electronics applications.

Transparent conducting materials (TCMs) are useful for many applications such as solar cells, touch screens, and flexible electronics. Traditional TCMs such as Indium Tin Oxide (ITO) pose limitations due to limited availability, high cost and poor reliability. Nanowire/nanotube doped polycrystalline graphene composites are being explored as an alternative of ITO as they can overcome these challenges. We utilize percolation transport theory to study the electrical and thermal transport behavior in these composites. This will allow optimal design of the composite structure for improved electrical and optical properties.

About the speaker:

Man Prakash Gupta currently works a Postdoctoral Fellow in the Department of Mechanical Engineering at Georgia Institute of Technology, Atlanta, USA. He completed his Ph.D. in Mechanical Engineering in 2014 at the same place. Man Prakash obtained his B.Tech. - M.Tech. dual degree in Mechanical Engineering at Indian Institute of Technology Kanpur in 2009. His current research work is focused on the electrical, thermal and electromagnetic energy transport and dissipation in emerging electronic materials/devices with the goal of understanding their properties and improving their behavior under external stimuli. Man Prakash is a recipient of multiple awards including the Best Ph.D. Thesis Award at Georgia Tech, the Best Paper Award from IEEE, and the Best Poster Awards from ASME

Wednesday, Apr 13, 2016, Time: 5:15 PM, Venue: FB 370

 

Dr. Junghyuk Ko, Post Doctoral Research Associate, Department of Mechanical Engineering, University of Victoria, Canada

"Melt Electrospinning using Polycaprolactone (PCL) Polymer for Various Applications:Experimental and Theoretical Analysis"

Abstract:

This study presents a melt electrospinning technique to fabricate highly porous and controllable poly (ε-caprolactone) (PCL) microfibers for
tissue engineering applications and rehabilitation applications. Electrospinning without solvents via melt methods may be an attractive approach to tissue engineering of cell constructs where solvent accumulation or toxicity is an issue. This method is also able to produce microfibers with controllable parameters. However, the fiber diameters resulting from melt electrospinning processes are relatively large when
compared to the fibers from solution electrospinning. The typical microfiber diameter from melt electrospinning was reported to be approximately 0.1mm. In order to further develop the melt electrospinning technique, we focused on the design of a melt electrospinning setup based on numerical analysis using the Solidworks 2013 simulation package and practically established a melt electrospinning setup and thermal control system for accurate experiments. One of main purposes of this study is the build-up of mathematical modeling to control and predict the electrospun microfiber via a more intricate understanding of their parameters such as the nozzle diameter, applied voltage, distance between the nozzle and counter electrode, temperature, flow rate, linear transitional speed, among others. The model is composed of three parts: 1)melt electrospinning process modeling, 2) fibrous helix movement modeling, and 3) build-up of microfibers modeling. The melt electrospinning process model describes an electric field, the shape of jet’s continuously changing shape, and how the polymer melt is stretched into a Taylor cone and a straight jet. The fibrous helix movement model describes movement of electrospun microfibers influenced by Lorentz force, which moves along the helix pattern. Lastly, the build-up microfiber modeling describes the accumulation of the extruded microfibers on both flat and round counter electrodes based on the physical forces involved. These models are
verified by experimental data from our own customized melt electrospinning setup. Moreover, the fabricated scaffolds are tested by seeding neural progenitors derived from murine R1 embryonic stem cell lines and it demonstrates the potential of scaffolds for tissue engineering applications. To increase cell attachment and proliferation, highly porous microfibers are fabricated by combination of melt electrospinning and particulate leaching technique. Finally, auxetic stretchable PCL force sensors are fabricated by melt electrospinning for hand rehabilitation. These stretchable sensors can be used to measure applied external loads or displacement and are also attachable to various substrates. We have attempted to apply the sensors to real human hand in order to prove their functionality.

About the speaker:

Dr. Junghyuk Ko received the Bachelor degree in biomedical engineering from the Konkuk University, Korea, in 2006, the Master of Applied Science and Doctor of Philosophy degrees in mechanical engineering from University of Victoria, in 2010 and in 2014 respectively. Presently, he is a postdoctoral research associate at the University of Victoria in the department of Mechanical Engineering. His interests include fabrication of biomedical scaffolds, electrospinning hybrid 3D printing.

Monday, Apr 11, 2016, Time: 5:15 PM, Venue: FB 370

 

Kiran Chandra Sahu, Aalto University, Finland

"Vibration and Active Structural Acoustic Control of Sandwich Structures"

Abstract:

In this talk, I will speak about my expertise on “Acoustics and Vibration” with the main focus on the projects I have carried out in my short research career. I worked on various projects in different capacities, but the standout works are “Dynamic instability regions of sandwich beam”, “Construction of structural actuators for active control of sound” and “Active control of sound transmission though sandwich structures”. Brief summary about these research topics are illustrated one by one as follows.

Use of sandwich beams with visco-elastic core has enormous applications in reducing the transmission of vibratory energy in mechanical systems. When structures are subjected to dynamic loading, for some values of excitation amplitude and frequencies, they may behave as parametrically excited systems. So, parametric instability regions need to be investigated to operate the system safely. Two types of three-layered symmetric sandwich beam subjected to a periodic axial load are studied. In the first, the middle layer is made of soft-core and in the other, the middle layer is consist of both soft-core and Magnetorheological Elastomer (MRE). The advantages of using MRE to actively control the vibration of the sandwich beam have also been studied in detail.

Like the vibration modes are orthogonal to the vibration field, radiation modes are orthogonal to the radiated sound field. Therefore, attenuating the amplitude of a radiation mode can give guarantee of reduction of sound radiation. This procedure is called as Active Structural Acoustic Control (ASAC). At low frequencies, radiation efficiency of the first radiation mode (volume velocity mode) is highest of all. Thus, specific actuators need to be designed to control this mode. For this application, two types of structural actuators, Elastic Mass Actuator and Magnetic Mass Actuator, are modeled, simulated and tested in the semi-anechoic and reverberation rooms with the main focus of reducing vibration of firewall in order to attenuate low frequency sound inside a car cabin and also in buildings close to noisy environment.

The greatest difficulty ASAC suffers is in finding an “optimal” error quantity, which can be easily implemented as the minimization quantity in
a control algorithm. Volume velocity control metric, which is generally used in ASAC, typically requires either a large number of sensors distributed across the entire structure, or a single distributed shaped sensor to accurately measure the volume velocity. A new parameter termed “weighted sum of spatial gradients (WSSG)” showed a great potential to significantly reduce noise transmission by using four sensors only. A comprehensive study on volume velocity and WSSG has been carried out, and the control strategies are implemented on soft-core sandwich panels and double panel partitions. Numerical calculations indicate that, by intelligent selection of modal indices for the calculation of WSSG and the frequency band for active control, WSSG is able to achieve comparable amount of sound attenuation with volume velocity.

I will conclude the presentation with my future plan of research and the subjects I would like to teach.

About the speaker:

Kiran Chandra Sahu is pursuing Postdoctoral studies at Aalto University (Finland) where he will defend his PhD thesis on 22nd April 2016. His PhD is also from the same place. He finished his undergraduate studies in Mechanical Engineering at University College of Engineering Burla, and Masters in Mechanical Engineering at IIT Guwahati. His research areas include Acoustics and Vibration. He has authored and co-authored 7 international journal publications and 8 conference papers and presentations.

Friday, Apr 08, 2016, Time: 5:15 PM, Venue: FB 370

 

Dr. Sudip Dey, Department of Mechanical Engineering, NIT Silchar

"Uncertainty Quantification is a myth or reality – A test drive for composite structures"

Abstract:

Uncertainties are unavoidable in the description of any real-life systems. There are several sources and forms of uncertainties, both in the mathematical models and in the experimental results. In general, an additional factor of safety is assumed by the designers due to difficulty
in quantifying those uncertainties. The existing common practice results in either an ultraconservative or an unsafe design. Uncertainties from a single source can propagate and influence to another parameters. Subsequently the reliability of the system cannot be ensured due to such cascading effects of the accumulated errors, unless the inherent uncertainties of the system are quantified. Otherwise, such variabilities can result in significant deviations from the expected output of the system. Hence uncertainty quantification (UQ) has practical importance to avoid any failure and simultaneously to insure the reliability of the system. The present discussion topic portrays the myth and reality of UQ in the light of laminated composite structures which has gained immense popularity in aerospace, marine, civil construction and automotive industries due to large specific strength and high specific stiffness properties. Due to the inherent anisotropy and complexity, composite structures are difficult to manufacture accurately according to its exact design specifications, resulting in undesirable uncertainties. The uncertainties in composites can be promulgated due to the variabilities inadvertently arising in their geometry, materials, environment and operations. Thus output responses of such system show the fluctuation from its deterministic value. Thus the structural reliability is subjected to considerable element of risk which can be arrested by UQ through efficient computational modeling of the system. The stochastic dynamic behaviours such as, stochastic natural frequencies, stochastic frequency response function, stochastic mode shapes are presented. The sampling size and computational cost is reduced by employing the present method compared to direct Monte Carlo simulation (MCS). The convergence studies and error analysis are carried out to ensure the accuracy of model. The flow charts are presented for different UQ models. A comparative study along with tests for validation and verification are conducted to justify the merit of different models for laminated composite plates and shells. Statistical analysis is presented to illustrate the results and their performances.

About the speaker:

Dr. Sudip Dey is at present working as Assistant Professor in Mechanical Engineering Department of National Institute of Technology Silchar, India from November, 2015. Previously, he was a Post-doctoral Researcher at Leibniz-Institut für Polymerforschung Dresden e. V., Germany, worked with Prof. Gert Heinrich (TU Dresden, Germany). Prior to that, he was a Post-doctoral Researcher at College of Engineering, Swansea University, United Kingdom, worked with Prof. Sondipon Adhikari. He obtained Bachelor in Mechanical Engineering Degree from Jadavpur University, India. He received Ph.D. (Engg.) degree from Jadavpur University, India. His field of specializations include Applied Mechanics and Design. He has more than ten years experience in research, teaching, industrial and professional activities. His research interests include uncertainty quantification, numerical investigation of fibre-matrix interaction, mechanics of composites, multi-scale and finite element analyses with an emphasis on computational modelling. He has several research publications in reputed international journals and conferences. (For more detail, please refer to https://sites.google.com/site/drsudipdey/)

Wedesday, Apr 06, 2016, Time: 5:15 PM, Venue: FB 370

 

Dr. Manjesh Kumar Singh, Department of Materials, ETH Zurich

"Simulation and Experimental Studies of Polymer Brushes under Shear"

Abstract:

Nature has its own complex way of lubricating sliding surfaces with the help of glycoproteins. In recent times mankind has tried to imitate natural lubrication using polymer brushes. Polymer molecules are attached by one end to a surface using different approaches (‘grafting to’ or ‘grafting from’); if the surface grafting density is so high that the polymer chains start to overlap, they stretch away from the surface
forming a polymer brush. The equilibrium brush height is larger than the size of the unperturbed chains in bulk solution. Polymer-brush-coated surfaces find applications in many fields including colloidal stabilization, adhesion, bio-compatibilization and tribology. The aim of
this work is to understand the underlying molecular mechanisms of frictional behavior of polymer brushes and gels in a good solvent by
employing complementary experimental and simulation studies.

The colloidal-probe-based lateral force microscopy (LFM) technique was employed for experimental investigations, and used to study the frictional behavior of PGMA (poly glycidyl methacrylate) brushes and gels in a dimethylformamide (DMF) solvent. Polymer brushes and gels were grafted on a silicon surface using SI-ATRP (surface initiated atom transfer radical polymerization) by another PhD student in the project. The ex-situ/post-modification method was used to fabricate PGMA gels of different degrees of crosslinking with two different lengths of
crosslinkers to facilitate the study of the effect of crosslinking on the frictional behavior of polymer brushes. The AFM-based nanoindentation
technique was employed to study the mechanical properties of PGMA brushes and gels in DMF.

Polymer brushes were modeled using a multibead-spring model and studied via molecular-dynamics (MD) simulations to understand their tribological behavior. The simulations were performed for two kinds of systems (i) brush-against-brush and (ii) brush-against-wall. Both implicit and explicit solvent-based approaches were employed in this work. Polymer chains were modeled as linear semi-flexible chains, randomly grafted on a planar surface with the help of tethered beads. In the first step, the polymer-brush-bearing surfaces (grafting surface and wall) were brought near to each other and allowed to equilibrate. In the next step, tethered beads were displaced at constant shear speed, keeping the separation between the brush bearing surfaces (brush and wall) constant. Simulations were performed over a range of shear speeds and separation between grafting surfaces (grafting surface and wall). Normal and shear stresses were calculated using the Irving-Kirkwood expression for the stress tensor. The coefficient of friction was defined as the ratio of shear and normal forces. Speed-dependent studies were carried out using an implicit-solvent approach for a fixed separation, whereas the separation-dependent studies were carried out at a fixed speed using an explicit-solvent approach. Simulations were performed on polymer brushes as well as gels for a combination of lengths of crosslinker chains and degree of crosslinking to facilitate the study of the effect of the crosslinking on the behavior of polymer brushes subjected to shear. Quantities extracted from the simulations were the normal and shear stresses, radius of gyration, density and velocity profiles and interdigitation for different combinations of shear speeds and separations between brush-bearing surfaces (brush and wall). At each stage, simulation results were compared with our experimental data to rationalize the behavior of end-grafted polymer chains under shear.

The combined experimental and simulation study offers a number of insights that will help to establish a framework for design rules for polymer-brush-based lubrication aiming at specific tribological properties.

About the speaker:

Dr. Manjesh Kumar Singh has recently completed PhD at Department of Materials of ETH Zurich in the field of Surface Science and Technology. His PhD thesis titled “Simulation and Experimental Studies of Polymer Brushes under Shear” involved complementary experimental and simulation studies to facilitate understanding of tribological behavior of polymer brushes and gels at molecular scale.
He studied Bachelor in Engineering in Mechanical Engineering from Indian Institute of Engineering, Science and Technology, Shibpur, India
(formerly BESU). Later, he studied at Indian Institute of Science, Bangalore, Master of Engineering in Materials Engineering. His master's
thesis was supervised by Prof. Vikram Jayaram and Prof. (Late) Sanjay K. Biswas.

Dr. Singh's research interests include computational mechanics and materials science, tribology and soft matter.

Friday, Apr 01, 2016, Time: 5:15 PM, Venue: FB 370

 

Dr. Debabrata Dasgupta, Research Associate, Department of Mechanical Engineering, IIT Kharagpur

"Homogenization based upscaling of electrokinetic transport in porous media"

Abstract:

Electrokinetics in porous media plays a pivotal role in a wide gamut of applications ranging from ion batteries, waste-water treatment, soil
dewaterification, water deionization etc. to transport in ultra-low cost diagnostic devices like paper-and-pencil based devices and paper based
fuel cells. The key to understanding the transport phenomena in suchdevices involves an appropriate resolution and subsequent interlinking of the coupled physics which spans over multiple length-scales. In the present talk, the pressure-driven electrokinetic transport of electrolytes
in porous media will be quantified through a matched asymptotic expansion based method, to obtain a homogenized description of the upscaled transport. The effective upscaled transport equations and coefficients will be obtained for both topographically simple and complex domains without and with the consideration of streaming potential. Subsequently, the influence of the microstructure topology, solid fraction, surface zeta potential and induced streaming potential on the modification of the Darcy's law will be discussed in connection to transport processes through porous plugs, clays and soils by considering a case-study on sandstone Berea.

About the speaker:

Dr. Debabrata Dasgupta completed his Ph.D. from IIT Kharagpur. He obtained his M.S. from IIT Kharagpur and his B.E. from Jadavpur University, Kolkata. Presently Dr. Dasgupta is working as a Research Associate in the Department of Mechanical Engineering at IIT Kharagpur. He has research interests in the area of Microfluidics and Micro/nano scale transport processes, and transport in multiphase and multiscale systems. He has several research publications including those in Applied Physics Letters, Soft Matter, Physical Review E, Physics of Fluids and Journal of Computational Physics.

Wednesday, Mar 16, 2016, Time: 5:15 PM, Venue: FB 370

 

Dr. Kaushik Saha, Post Doctoral Fellow, Argonne National Laboratory, USA

"Two-phase flows in automotive fuel injectors"

Abstract:

Two-phase flow inside and near nozzle regions of the automotive fuel injectors is an important area of research. Extreme low pressure regions develop in the high pressure direct injection fuel flow inside the fuel injector holes, compelling the liquid fuel to transform to vapor phase in the form of cavities or bubbles, a phenomenon known as cavitation. The cavitation phenomenon determines the quality of primary atomization and hence affects the performance of direct injection diesel or gasoline engines. A cavitation model, coupled with the mixture multiphase approach and RNG k-e turbulence, has been developed and implemented in the ANSYS Fluent platform for analyzing cavitation in diesel injectors. The model predictions were in decent agreement with the experimental findings. Comparison of the model predictions with those of other existing models such as, Schnerr & Sauer, and Zwart-Gerber-Belamri indicated that the developed model provides reasonable numerical predictions and does not have some of the fundamental drawbacks imbibed in the equations of the other existing cavitation models. The developed model has also been extended to execute a comparative analysis of diesel and biodiesel cavitation. At lower pressure differentials biodiesel cavitation prediction was lower than that of diesel, but at high pressure differentials both diesel and biodiesel cavitation patterns were comparable. For cavitation inception scenarios i.e. at low pressure differentials molecular viscosity appeared to be a dominant factor for the diesel versus biodiesel cavitation study. The developed model has also been extended to a three-dimensional fuel injector with a moving needle and the predictions were in accordance with the published results.

Gasoline direct injection (GDI) is a growing trend in the automotive sector for the past decade. High injection pressure, better fuel economy have provided the impetus to the developments of GDI systems. At low or part load conditions the in-cylinder pressures are often sub-atmospheric and thus, the heated (around 360 K) injected gasoline fuel is subjected to superheated conditions. In such scenarios bulk liquid fuel undergoes rapid transformation to bulk vapor and the phenomenon is known as flash boiling. Experimental studies have indicated that extent of flashing strongly depends on the degree of superheat. Previous studies indicated that flash boiling strongly affects the spray characteristics and combustion phenomena in GDI engines. A mixture multiphase model coupled with Homogeneous Relaxation Model (HRM) has been developed and implemented in the CONVERGE code for analyzing flash boiling problems. Reasonable agreements have been obtained with experimental findings and published numerical results. Best practices for running a flash boiling simulation using a Cartesian cut-cell method has been outlined. It has been found the model setup is capable of capturing the two-phase flow characteristics under different thermodynamic conditions, substantiated by prior thermodynamic calculations. The model has also been used to understand the needle lift effects on flashing patterns in GDI systems.

About the speaker:

Kaushik Saha is currently pursuing his postdoctoral research at Argonne National Laboratory, under supervision of Dr. Sibendu Som. At Argonne National Laboratory he is working on flash boiling phenomenon of Gasoline Direct Injection systems and internal combustion engine simulations for NOx reduction using air-separation membranes. Dr. Saha finished his undergraduate studies in Mechanical Engineering at Jadavpur University. He pursued his Masters in Mechanical Engineering at University of Connecticut, USA. During Masters he carried out numerical studies in the field of material processing in thermal plasmas. After his Masters, he completed his doctoral studies at University of Waterloo, Canada. At University of Waterloo Dr. Saha worked on topics such as, Urea-SCR for NOx reduction, blended diesel-biodiesel droplet evaporation and cavitation in diesel injectors. His PhD thesis focused on two-phase flow inside diesel injectors. He has authored and co-authored 7 journal publications and 12 conference papers and presentations. Dr. Saha was also a recipient of Outstanding Teaching Assistant award at University of Waterloo during his PhD.

Friday, Mar 11, 2016, Time: 5:15 PM, Venue: FB 370

 

Dr. A. Satya Narayanan, Indian Institute of Astrophysics, Bangalore, India

"Coronal Oscillations - Theoretical Perspectives"

Abstract:

In this talk, we discuss a method by which Magnetic Fields which are prevalent in the Sun’s Atmosphere, namely, the Corona, can be calculated with the Kink Oscillations, which is basically an MHD (Magneto Hydro Dynamic) wave. Kink Oscillations are found in structured media, in particular in cylindrical geometries, which are modeled in the Coronal Loops. The MHD equations are linearized and the solution of the resulting wave equation, is written in terms of Bessel Functions. The boundary conditions (continuity of velocity and total pressure) at the interface of the cylinder are applied. The resulting dispersion relation is a complicated transcendental function. Analytic solutions of this relation are hard to find. However, in the limit of large wave numbers, ka → ꝏ, the dispersion relation can be simplified and an analytic solution of this relation can be found. Using the phase velocity of the Kink Oscillations, and a few parameters such as the loop length, the density ratio and the frequency (or period), one can determine the magnetic field. The dispersion relation with the effect of uniform flows has also been derived.

About the speaker:

Dr. A. Satya Narayanan is presently an Associate Professor at the Indian Institute of Astrophysics, Bangalore, India. He obtained his undergraduate and graduate degrees in Mathematics from the University of Madras in the years 1976 and 1978, respectively. In the same year, he joined the Indian Institute of Science, Bangalore for pursuing his Doctoral degree at the Department of Applied Mathematics and successfully defended his thesis on "Studies on Internal Atmospheric Gravity Waves and their Stability Characteristics". He was awarded the Ph.D. Degree in Dec. 1982.

In January, 1983, he joined the Center for Atmospheric Sciences, Indian Institute of Science, as a Research Associate and worked on problems related to jets, solitary waves, Rossby waves. He returned to the Department of Applied Mathematics in Dec. 1984 as one of the Research Scientists , chosen by the University Grants Commission, New Delhi, India. After completing the tenure of five years, he briefly joined the Mathematics Department as a Research Associate.

He joined the Indian Institute of Astrophysics, initially as a Visiting Fellow in 1990, was regularized and rose to the present position. He has publications in peer reviewed national and international journals. He is one of the Editors of the Proceedings of the International Conference on Spectroscopy, held at Kodaikanal, published by Springer in 2010. He is also the author of a textbook, 'An Introduction to Waves and Oscillations in the Sun’, which has been published by Springer in 2013. He has also written a book in collaboration with Prof. S.K. Saha of IIA,
titled "Waves and Oscillations in Nature – An Introduction", published by CRC Press (Taylor and Francis) in 2015.

Wednesday, Mar 09, 2016, Time: 5:15 PM, Venue: FB 370

 

Dr. Deepu P, Postdoctoral Fellow, TIFR Hyderabad

"Oscillation of droplets suspended in a convective flow field"

Abstract:

The first step on the way to understanding the complicated dynamics of spray is to study the behavior of isolated droplets. In many industrial
and natural processes such as turbulent combustion, agricultural sprays, spray cooler, falling raindrops and cloud evolution the droplet is subjected to a chaotic unsteady external flow field. The interaction between the liquid and gaseous phases results in very intricate droplet dynamics like capillary instabilities, atomization, droplet collision and coalescence and vaporization, to name a few. In this talk, the focus is on shape oscillations dynamics of droplets subjected to an external convective flow field. Such a droplet will exhibit different modes of shape oscillation; the competition between capillary forces and the aerodynamic forces is primarily responsible for these oscillations. By decomposing the droplet shape into Legendre modes, the shape oscillations exhibited by a droplet hanging from the junction of cross-wire placed at the center of an air jet is studied. Both high-speed imaging and hot-wire anemometry are employed to prove that the driving force of oscillation of droplets subjected to the air jet is in fact the inherent pressure fluctuations in the jet and the vortex shedding has minimal role to play in the range of Reynolds number investigated. The effect of surface tension, viscosity and Reynolds number on the shape oscillation level has been examined. The first experimental evidence of viscous attenuation of lower frequencies in a particular mode in glycerol/water mixture is reported. A theoretical model was developed to simulate the droplet shape oscillations induced by an external flow with broadband energy spectrum, as measured in the experiment. This model, albeit a linear one, further corroborates the conclusions drawn from the experiment. The effect of additional possible features in the ambient flow fields like pulsatile and vortical disturbances were also investigated using the model. The time of interaction of the droplet with an eddy in the flow is found to be very crucial in determining the amplitude of oscillation of the droplet. The shorter the interaction time, the higher are the chances of the droplet oscillation being pushed into resonance.

About the speaker:

Dr. Deepu P is currently working as a postdoctoral fellow at TIFR Hyderabad. Prior to joining TIFR, he completed two postdoctoral fellowships at department of Mechanical and Aerospace Engineering, University of Florida and Interdisciplinary Centre for Energy Research, Indian Institute of Science. He holds a Ph. D. in Mechanical Engineering from Indian Institute of Science, where he was awarded Professor B.K. Subba Rao Medal for best PhD thesis in 2014. He received his B.Tech degree from Mahatma Gandhi University, following which he had a four-year stint at ISRO as a scientist/engineer. His research interests include cloud physics, biophysical aerodynamics, droplet dynamics, hydrodynamic instability, transport processes in porous media, absorption enhancement and multiphase flow.

Friday, Mar 04, 2016, Time: 5:15 PM, Venue: FB 370

 

Dr. Abhilash J. Chandy, University of Akron, Ohio, USA

"Direct numerical and large eddy simulations of stratified turbulent flows"

Abstract:

Stratified fluid is a fluid with density variation in the vertical direction of gravity. There are many instances in nature and technology in which flows are strongly affected by stable density stratification. For instance, propagating internal gravity waves owe their existence to the presence of a restoring buoyancy force, and turbulence, especially in its later stages of decay, can be dominated by the presence of a stabilizing stratification. In the atmosphere and oceans, flows on intermediate scales are usually strongly influenced by stable stratification. In the presence of such phenomena, fluids undergo slow quasi-horizontal vortical motion, and in addition, the buoyancy forces tend to damp the turbulence. Besides stratification, a mean non-zero helicity may also present in any geophysical environment, for instance in storm systems. It has been known that helicity slows down the energy transfer from large scales to small scales in stably-stratified turbulence. Due to the importance of helical and non-helical stratified turbulence in the ocean and atmosphere, it has been a subject of tremendous interest for a lot of researchers.

Fully-resolved or direct numerical simulations (DNS) can provide invaluable insights into the energy scaling and cascade processes in stratified turbulence. However, DNS is inapplicable to the typically high Reynolds numbers (Re) observed in geophysical flows, due to the increased computational expense. Large eddy simulation (LES) overcomes this limitation by filtering out all scales of motion larger than a cutoff filter width, while smaller scales are represented using sub-grid-scale (SGS) models. DNS of weakly and strongly stratified decaying homogeneous turbulence are presented for two transition-to-turbulence cases with different initial conditions: the non-helical Taylor-Green vortex (TGV) and the helical Arnold-Beltrami-Childress (ABC) configurations at varying Froude numbers (Fr), where Fr marks the relative importance of density stratification for decaying turbulence. Furthermore, SGS turbulence models for LES are quantitatively assessed through comparisons to in-house DNS.

About the speaker:

Dr. Abhilash J. Chandy is an Associate Professor in Mechanical Engineering at The University of Akron, Ohio in the USA. He received his Masters in Aerospace Engineering at University of Florida in Gainesville, Florida, and Doctoral degree in Mechanical Engineering from Purdue University in 2007. At The University of Akron, Dr. Chandy has been involved in research activities concentrating on computational fluid dynamics of (CFD) of fundamental problems in stratification and magnetohydrodynamics, where turbulence models are developed and tested for scalability and performance, and industrially-relevant topics such as manufacturing and tire acoustics, where CFD modeling is utilized to improve efficiency and reduce tire noise, respectively. Focus is also on the development of model implementations for modern computing architectures like graphics processing unit (GPU) applied to turbulence modeling and chemical kinetics solution algorithms. Research projects at Dr. Chandy’s Mathematical Modeling and High-Performance Computing Lab (MathModHPCL) have been funded by federal agencies such as the National Science Foundation (NSF) and the Air Force Office of Scientific Research (AFOSR), and also industrial partners such as Goodyear, Babcock and Wilcox, Kraton polymers and Sherwin-Williams.

Wednesday, Mar 02, 2016, Time: 5:15 PM, Venue: FB 370

 

Dr. Kazuya TATSUMI, Department of Mechanical Engineering and Science, Kyoto University, Japan

"Microfluidic technologies for blood cell sensing and sorting."

Abstract:

Microfluidics have innovated various application in terms of miniaturizing the system, reducing the measurement time and cost, and enhancing the accuracy, and have made a large contribution to the fields of medicine and biology. We have been working on developing a microfluidic device which can measure the blood cells deformability and sort the specific cells from others with high throughput (1000cells/s). The device consists of microchannel flows producing the sheath and elongational flows, cell electric resistance sensor using micro-electrodes and dielectrophoretic cell collecting-aligning-sorting system employing the rail-type, ladder-type and flip-type electrodes.
In this talk, I will introduce the measurement and sorting physics, fabrication procedure, numerical modeling and discuss the results and the performance of our microchip.

About the speaker:

Dr. Kazuya TATSUMI has received M.S., and Ph.D. degrees in 1999 and 2003 from the Department of Mechanical Engineering of Kyoto University. He worked in Osaka prefecture University during 2003-2006 as Assistant Professor and Kyoto University during 2003-2006 as Assistant Professor, and was promoted to Associate Professor of Mechanical Engineering and Science of Kyoto University. He has been a Visiting Scholar at AGH University (Poland) in 2007. His current research activities and interests include the development of microfluidics platforms with the functions of cell sorting using dielectrophoretic forces, RBC deformability sensors using impedance measurements, development of mechanical models of blood cells, heat and mass transfer in viscoelastic fluids, and analysis of thermal physics in thrombus generation.

Monday, Feb 29, 2016, Time: 5:15 PM, Venue: FB 370

 

Dr. Avishek Ranjan, Department of Engineering, University of Cambridge

"Structure formation due to the dispersion of inertial waves in rapidly rotating turbulence."

Abstract:

Rotation imparts elasticity to a system so that the Coriolis force acts as the restoring force (a consequence of angular momentum conservation in the inertial frame of reference). The resulting oscillations are called inertial waves. Localized turbulence under rotation frequently occurs in nature and practice. Columnar flow structures that resemble Taylor columns have been observed in several investigations on rotating turbulence; however their mechanism of formation remains a subject of debate. In the talk, the role of inertial waves in the formation of columnar structures (by using a layer or 'cloud' of localized turbulence) will be discussed. Recent results from the DNS of a turbulent cloud under rapid rotation will be presented. Using helicity as a diagnostic, it can be shown that the columnar structures are actually low-frequency inertial wave-packets. A spatiotemporal analysis using proper orthogonal decomposition and discrete Fourier transform reveals significant off-axis radiation of inertial waves apart from the columnar modes which travel parallel to the rotation axis. The implications of this study for the Earth's 'turbulent' outer core will also be discussed.

About the speaker:

Dr Avishek Ranjan is a postdoctoral research associate in the department of Engineering at the University of Cambridge, presently working on ‘spherical rotating magneto-convection’ with Professor Peter Davidson. He completed his PhD in the same department in June 2015. His doctoral thesis was on ‘inertial waves in rotating turbulence’ (about which he will talk today). Before his PhD, he completed a MS (by research) in the I C Engines laboratory at IIT Madras when he worked on incylinder optical flow diagnostics under the supervision of Prof Pramod S Mehta and Prof S R Chakravarthy. Along with his MS research at IITM, he also worked as a project associate in a TIFAC-DST sponsored project on ‘the use of straight vegetable oils in engines’ with Prof Mehta. Prior to IITM, he was an assistant manager in the connecting rod & camshaft manufacturing line at Tata Cummins Ltd. Jamshedpur for a year, after completing his B.Tech. (Mechanical engineering) with a Gold medal from NIT Jalandhar.

Friday, Feb 26, 2016, Time: 5:15 PM, Venue: FB 370

 

Dr. Rajesh Kitey, Department of Aerospace Engineering, Indian Institute of Technology, Kanpur

"Laser spallation: A novel technique to study fracture in thin films"

Abstract:

Several experimental methods such as tension, compression and shear tests are well established to characterize mechanical behavior of materials under quasi-static loading conditions whereas the impact, split-hopkinson bars and explosion tests are some of the generally adopted techniques for determining dynamic material characteristics. Although the test methods have been satisfactorily standardized for conducting experiments at macro-scale, any such methodologies have failed to evolve for the cases when the material dimensions are constrained to micro- and nano- levels. Also, the conventional techniques can only provide average macroscopic behavior of materials with the microscopic mechanisms, especially in regards to the failure, being largely obscured. Micro- and nano- sized materials have a range of engineering applications. For example thin films are key component of microelectronics devices while they are also extensively used in aerospace applications as adhesive layers. Typically, sensors and some of the aircraft components that cannot be fastened to the base structure by riveting, bolting or welding due to smaller sizes and/or complex shapes, are bonded using polymeric adhesives. The reliability of these joints is inevitably governed by the material and the interfacial failure properties of the adhesive layer. The failure behavior of such components complicates when they are subjected to extreme dynamic loading conditions. Therefore, prior to design and fabrication of multilayer structures dynamic cohesive, adhesive and interfacial fracture characteristics of the adhesive materials should be determined.

In the seminar a novel Laser Spallation Technique to load materials at extremely high strain rate (of the order 10^7 /s) using laser induced stress waves will be presented. The working principle with details of nano-scale inetreferometric measurements will be provided. The adaptability of the method to characterize fracture behavior of metallic, polymer and ceramic film interfaces will be reviewed. The experimental technique’s capability of mixed-mode loading along with its extension to characterize materials’ dynamic strength parameters will be discussed.

About the speaker:

Dr. Rajesh Kitey is a faculty in Aerospace Engineering department at IIT Kanpur since 2010. Prior to joining at IIT Kanpur he worked at Penn State Dubois as an Assistant Professor for 1 year. He obtained PhD degree from Auburn University, USA and has Postdoc experience from the University of Illinois at Urbana-Champaign. His areas of interests include quasi-static and dynamic fracture in heterogeneous materials, Dynamic wave propagation in anisotropic media and interfacial fracture characterization in multilayer thin films.

Wednesday, Feb 10, 2016, Time: 5:15 PM, Venue: FB 370

 

Prof. Dr. Amitabha Bandyopadhyay, Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur

"Osteoarthritis: A case of wrong development at the wrong place"

Abstract:

One of the major objectives of my laboratory is to develop novel therapy for osteoarthritis. Almost 65% of 65 and above Indians suffer from the debilitating disease affecting joints of hands and legs, primarily the knee joints and hip joints. This disease, though not fatal, causes massive economic loss due to loss in productivity and compromises quality of life. Early signs of osteoarthritis often appear in mid-40s to early 50s and the disease gets progressively worse with age. At present there are only two types of therapy available: (i) Symptomatic – where the pain is managed through administration of pain-killers and (ii) Radical surgery – where the natural joint is replaced by prosthesis. Symptomatic treatment ceases to be effective after a certain point while joint replacement is very expensive and often requires corrective follow-up surgeries.

The tissue affected in osteoarthritis is referred to as joint cartilage and it undergoes many changes during the disease. It is not clear whether the disease associated changes are the causes of the disease or the result of the disease. I will explain why I view osteoarthritis as an aberration arising out of triggering an embryonic developmental process in adult life. This hypothesis arises out of our recent proposition of a new paradigm of joint cartilage development. I will demonstrate that the tissue affected in this disease is mechanosensitive and will narrate the importance of this issue in development of novel therapies for osteoarthritis.

About the speaker:

Amitabha Bandyopadhyay graduated with an honors in Chemistry from Presidency College, Kolkata in the year 1992. Subsequently, he attended the Biochemistry MSc program of Calcutta University. In 1995, he joined the laboratory of Prof. Umadas Maitra at Albert Einstein College of Medicine in New York for his doctoral research. For his PhD thesis he investigated the role of eukaryotic translation initiation 3 (eIF3) in protein synthesis. Upon receiving his PhD in 2002 he joined the laboratory of Prof. Clifford Tabin at Harvard Medical School for his post-doctoral research. During his postdoctoral work he used mouse genetics and chick molecular embryological techniques to study cartilage and bone development. Amitabha joined the faculty of BSBE in December 2006. He is interested in understanding the molecular mechanism regulating the development of bone and joint cartilage. Several skeletal disorders result from improper development and/or maintenance of bone and articular cartilage such as osteoarthritis and osteoporosis. His group studies the molecular basis of these disorders using transgenic mouse and chicken as model systems.

Thursday, Feb 04, 2016, Time: 4:00 PM, Venue: FB 370

 

Vinamra Agrawal, Department of Mechanical Engineering, California Institute of Technology.

"Materials under extreme environments: damage mitigation and energy harvesting"

Abstract:

Shock waves are typically generated in a material when it is subjected to a high velocity impact or a blast. These waves are characterized as propagating discontinuities across which material properties and states jump. They can cause the material to achieve very high stress states, and if transmitted without mitigation, it can lead to failure of key components. An important question here is 'Can we design materials which can successfully mitigate damage?' Another important question is 'Can we exploit the energy associated with shock waves for other applications?'.

In this talk, I will discuss my work on shock propagation in composites and ferroelectric materials. We try to understand the interplay between the length scale of the heterogeneities and the length scale associated with the wave front thickness. We study the phenomenon of scattering by solving an impact problem on a layered (not-necessarily periodic) material. We obtain analytic solution to the impact problem and comment on optimal design parameters for the composite. Additionally, we characterize the effective behavior of a random medium by studying front propagation in a stationary ergodic medium. We characterize the oscillations of a moving front and obtain probabilistic bounds on the front roughness. Next, we study the nonlinear electro-thermo-mechanical coupling of ferroelectric materials and study shock induced phase transitions, depolarization and energy harvesting through current generation. We develop a continuum framework to explain the physics behind pulsed power generators and shock induced phase transitions. We obtain current profiles from the analysis and compare them with experiments. Finally, I will discuss our current efforts, open problems and many directions which are to be explored in the future.

About the speaker:

Vinamra Agrawal is a PhD candidate in the Department of Mechanical Engineering at California Institute of Technology. He received his Masters in Mechanical Engineering from Caltech in 2012. He graduated from IIT Kanpur in 2011 with a Bachelor in Technology in Mechanical Engineering. His areas of interests include understanding the mechanics of heterogeneous materials, ferroic and multiferroic materials, and engineering new materials with targeted properties.

Wednesday, Jan 27, 2016, Time: 5:15 PM, Venue: FB 370

 

Dr. Asim Tiwari, Department of Mechanical Engineering, IIT Bombay

"Micromechanics Approach to Property Degradation in CFRP under Cyclic Loading"

Abstract:

Fatigue is the major failure mode for any structure under cyclic loading. In particular, composite materials exhibit highly complex damage mechanisms and are often overdesigned due to lack of understanding under cyclic loading. Many theoretical models exist in the literature for modelling and predicting the mechanical property degradation behavior under cyclic loading. All such models use some or the other kind of notional internal damage parameter which keeps growing with fatigue cycles. However, the growth of these damage parameters are themselves defined by the mechanical property degradation. Hence these models do not have a true predictive capability for mechanical property degradation. In this talk, true 3D quantitative measurement of microstructural damage in CFRP under cyclic loading is discussed. Damage micromechanisms viz., fiber breakage, matrix microcracking, debonding, and fiber pullout can be directly estimated and used in models to predict the property degradation via micromechanics. This is for the first time that property degradation in CFRP under cyclic loading are modeled with independently measured damage parameters

About the speaker:

Asim Tewari is professor in the department of Mechanical Engineering at IIT Bombay and In-Charge of National Centre for Aerospace Innovation and Research (NCAIR). Prior to this he was a staff researcher at General Motors Global R&D center in Bangalore. He graduated with a bachelor’s degree in Materials and Metallurgical Engineering from IIT Kanpur, India followed by MS and PhD from Georgia Institute of Technology, Atlanta. After his doctorate he was briefly with National Aerospace Laboratories. Subsequently, he joined IIT Kanpur where he served as assistant professor before joining General Motors Global R&D center in Bangalore. At IIT Bombay he has been instrumental in setting up several state-of-the-art facilities, including 3D x-ray microscopy laboratory, advanced thermo-mechanical simulation laboratory and Microstructural Mechanics laboratory.
His area of research is in mathematical models for microstructural-mechanics. He has over 50 peer reviewed journal publications and 9 international patents. His pioneering work in 3D microscopy has been widely cited including reproduction in ASM handbooks. He is in the editorial board of several international Journals including Metallurgical and Materials Transactions and Image Analysis & Stereology. He has served as advisory committee member for various national & international research boards and conferences. He has won several awards and recognitions for his research and teaching.

Friday, Jan 15, 2016, Time: 5:15 PM, Venue: FB 370

 

Dr. Mayank Kumar, MIT, USA

"Multiscale CFD Simulations of Entrained Flow Gasification"

Abstract:

Gasification of solid feedstocks is a popular methodology for the production of useful chemicals and synthetic fuels. Lately, gasification has gained popularity as a viable option for clean energy generation from coal via Integrated Gasification Combined Cycle (IGCC) plants. However, the design of gasifiers and their operation has largely been an experience based enterprise. Most, if not all, industrial scale gasifiers were designed before it was practical to apply CFD models. Moreover, gasification CFD models developed over the years may have lacked accuracy or have not been tested over a wide range of operating conditions, gasifier geometries and feedstock compositions. One reason behind this shortcoming is the failure to incorporate detailed physics and chemistry of the coupled non-linear phenomena occurring during solid fuel gasification. Moreover, in a multiphysics problem like gasification modeling, one needs to balance the effort expended in any one submodel with its effect on the accuracy of predicting some key output parameters.

Focusing on the aforementioned considerations in this seminar, I will describe the bottom-up construction of my multiphysics CFD gasification model, emphasizing the validation of the turbulence and char consumption models. The integrated model is validated with experimental data from various pilot-scale and laboratory-scale gasifier designs, further building confidence in the predictive capability of the model. Finally, the validated model is applied to conduct a sensitivity analysis on the MHI and GE gasifiers. The model is demonstrated to provide useful quantitative estimates of the expected gain or loss in overall carbon conversion when critical operating parameters such as feedstock grinding size, gasifier mass throughput and pressure are varied.

About the speaker:

Mayank Kumar holds a BTech from IIT Kanpur and MS/PhD from MIT, all in Mechanical Engineering. His research interests include clean coal technology, reacting multi-phase flows, energy conversion systems, radiative transport, statistical inference and data science. He also has a 360 degree experience of the industry, having worked in the Oil & Energy sector and founded a data-science enabled internet technology startup.

Wednesday, Jan 06, 2016, Time: 5:15 PM, Venue: FB 370

 

Prof. Dr. Amitabh Narain, Michigan Technological University, Houghton, USA

"Experimental and Modeling Results for Flow-Boilers (and Flow Condensers) that Operate in Wavy Annular Thin Film Flow Regimes and at High Heat-Flux Values"

Abstract:

This presentation summarizes experimental and modeling results in the context of applications of shear driven (including zero/micro-gravity flows) annular regime operations of milli-meter scale innovative flow-boilers and condensers. Besides describing the innovative operations, the presentation summarizes more recent computational and experimental results obtained for annular/stratified internal boiling and condensing flows. The reported results come from experiments as well as from a new fundamental scientific computational tool. The computations yield accurate numerical solutions of the full two-dimensional steady and unsteady governing equations.

The results highlight: (i) experimental ways for realizing high amplitude wavy annular thin film flows, (ii) differences in flow physics for shear driven (horizontal channels) and gravity driven (inclined channels) flows, (iii) non-linear stability analyses based identification of annular to plug-slug transition boundary, (iv) summary of the correlations developed to predict heat-transfer rates and the length of the annular regime, and (v) discussions of contact line flow-physics and acoustics enabled standing wave formations that are needed for very high heat-flux operations.

The talk also relates the science to technologies that can address cooling needs for devices operating at high heat-load and high heat-flux (≥1 kW/cm2) values. The fact that innovation needs change to air-side flows across larger scale boiler and condenser operations (that are used in power-plants and co-generation units) are discussed next. Ongoing research addressing these innovation needs are described.

About the speaker:

Dr. Amitabh Narain is currently Professor in the department of Mechanical Engineering at Michigan Technological University, Michigan, United States. There he leads the Energy Thermo-Fluids Group. He completed his B.Tech in Aerospace Engineering in 1978 from the Indian Institute of Technology, Kharagpur, India. He then completed his masters research in 1980 at University of Minnesota and continued with his Ph.D. in the same place and completed it in 1983. Dr Narain is an ASME Fellow and an Associate Editor of Journal of Heat Transfer.

Narain’s current research interests are both experimental and theoretical/ computational in nature and emphasize the area of phase-change flows – especially internal condensing and boiling flows. His secondary interests are in related areas of transport processes. These include cavitation signatures in an automobile’s torque-converter, melting and solidification processes associated with use of phase-change materials (PCM) for energy storage applications, and computational simulations of forced and natural convection turbulent flows (inside heat exchangers, displacement pumps, etc.).

Monday, Jan 04, 2016, Time: 5:15 PM, Venue: L1

 

Dr. Ramesh Narayanaswamy, Curtin University, Perth, Australia

"The Fluid Dynamics and Heat Transfer of Unsteady Impinging Jets"

Abstract:

In this seminar, Ramesh will cover some aspects of the current work done by the research team of the Fluid Dynamics Research Group at Curtin University. The presentation will include both computational and experimental work, bringing out the fluid dynamics as well as heat transfer characteristics. The unsteady flow structures generated by means of active surface vibrations, in combination with the issuing jet is explored in detail. The aim of the work is to focus on, and exploit hidden passive synergies that could be utilized for the quality as well as the quantity of heat removal from the target surface.

This project is supported by the Australian Research Council through its Discovery Project scheme.

About the speaker:

Dr. Ramesh Narayanaswamy is currently Associate Professor at Curtin University, located at Perth in Australia. Ramesh completed his MS Research in 1995 and PhD in 1999 from the Indian Institute of Technology Madras working with Prof. S.P. Venkateshan. Upon completion of his PhD, he undertook postdoctoral research with Prof. Wolfgang Merzkirch as a DFG postdoctoral fellow at the University of Essen, Germany during 1999-2000 working on optical methods in fluid dynamics and heat transfer. Prior to joining academia, he has worked as a Scientist at the Vikram Sarabhai Space Centre, Trivandrum (1990-1993), and at the National Aerospace Laboratories, Bangalore (2001-2004) totalling about 7 years. He commenced working as a Lecturer with Curtin University since 2004. Ramesh began his research career working on the interaction of radiation and natural convection problems applicable in the area of electronic cooling. His research interests include: natural convection and radiation, microchannel heat transfer, electronic cooling, jet impingement heat transfer. He is currently working on unsteady impinging jets, to study the fluid dynamics and heat transfer of pulsating flows.

Although his research includes computational and experimental heat transfer, he prefers to do experiments than computational work. He currently teaches Fluid Flow Modelling for 3rd year undergraduate students, and Measurement Science and Technology for 4th year undergraduate and postgraduate students, apart from supervising PhD students. He is currently the Acting Head of the Mechanical Engineering Department at Curtin.

Seminars : Fall 2015-16

Monday, Dec 28, 2015, Time: 5:15 PM, Venue: FB 370

 

Dr. Kaushik Banerjee, Staff Scientist, Oak Ridge National Laboratory, USA

"Used Nuclear Fuel Storage, Transportation, and Disposal: The US perspective"

Abstract:

As the largest multiprogram science and energy laboratory of the US Department of Energy (DOE), Oak Ridge National Laboratory (ORNL) is engaged in a wide range of activities that support DOE’s mission: ensuring America’s security and prosperity by addressing its energy, environmental, and nuclear challenges through transformative science and technology solutions. The Reactor and Nuclear Systems Division (RNSD) of the Nuclear Science and Engineering Directorate at ORNL, provide science and technology to address issues facing the current and future utilization of nuclear reactors and the supporting nuclear systems infrastructure. This talk will provide a brief overview of the research portfolio of RNSD with emphasis on spent nuclear fuel (SNF) related research and activities. The current SNF management practices in the US will be discussed in details with relevant background information. The talk will also include some of the science and engineering challenges facing the current US and international SNF management programs.

About the speaker:

Dr. Banerjee is a staff scientist in the Used Fuel Systems group at Oak Ridge National Laboratory (ORNL). Banerjee received a Ph.D. in nuclear engineering and radiological sciences from University of Michigan in 2010. Banerjee started his professional nuclear engineering career at Holtec International in 2010. Banerjee joined ORNL in 2013 as an R&D staff member. Banerjee leads the technical development of Used Nuclear Fuel-Storage, Transportation & Disposal Analysis Resource and Data Systems (UNF-ST&DARDS), which provides a comprehensive SNF database and integrated analysis tools. At ORNL, Banerjee also leads the criticality aspect of the feasibility determination of the direct disposal of already loaded SNF casks and supports many other projects.

Wednesday, Dec 23, 2015, Time: 5:15 PM, Venue: FB 370

 

Prof. R. Narasimhan, Department of Mechanical Engineering, Indian Institute of Science, Bangalore

"Cavitation induced failure in brittle bulk metallic glasses"

Abstract:

Bulk Metallic Glasses (BMGs) have many attractive properties like high strength, stiffness and corrosion resistance. They have many potential engineering applications like in biomedical devices, sporting goods and defense equipment. However, they may exhibit poor fracture resistance which can impede their usage in structural components. A detailed understanding of the physical mechanisms that govern fracture in BMGs remain elusive. This lecture will focus on a cavitation induced failure mechanism which has been observed in brittle BMGs.

Mode I fracture experiments were recently conducted using annealed Vit-I (a Zr-based BMG) specimens. It was found that brittle fracture occurs and the fracture surface exhibits several interesting features. While HRSEM pictures show some evidence of nano-scale void nucleation close to the original ntch front, further away, perodic nano-scale corrugations are noticed. Such fractoraphic features have also been reported by other investigators for inherently brittle (like Mg-based) BMGs. Atomistic simulations show shear band mediated plastic flow and intense crack blunting in a ductile (Cu-Zr) BMG, whereas brittle fracture by a cavitation mechanism is noticed for a brittle (Fe-P) BMG. The latter exhibits several intriguing features such as a low cavitation stress to yeild stress ratio and void-insensitive cavitation behaviour. These are attributed to nano-scale fluctuations in atomic density that are present in the britttle BMG which give rise to weak regions with low yield strength.

Motivated by the above observations, 2D plane strain continum finite element analysis of cavitation in a heterogenous plastic solid containing a distribution of weak zones is performed to understand all features pertaining to nucleation of cavities in brittle BMGs. It is found that the presence of weak zones can significantly reduce the critical hydrostatic stress corresponding to onset of cavitation which is controlled uniquely by the local yeild properties of the weak zones and the prevailing stress state. The volume fraction of weak zones and stress state influence the nature of cavitation bifurcation. The results also show that snap-cavitation occur in heterogenous plastic solids, giving rise to sudden formation of voids with finite size, which does not happen in homogeneous plastic solids. Continnum simulations of crack initiation under mode-I plane strain, small scale yielding conditions in a heterogeneous plastic solid are also performed and various steps involved in cavitation-induced fracture are delineated.

About the speaker:

Professor Narasimhan Ramarathinam received his Ph.D. in Applied Mechanics from California Institute of Technology in 1986. He worked at Indian Institute of Technology, Mumbai, for four years before joining the Mechanical Engineering Department at Indian Institute of Science, Bangalore, in 1991. His research interests include Computations Mechanics and Materilas Science, Fracture Behaviour of Materials and Indentation Mechanics. He has published more than hundred articles in refereed international journals and guided the thesis dissertation of about twenty research students, He is a Fellow of Indian Academy of Science, Indian National Science Academy and Indian National Academy of Engineering, He had served on the editorial board of many journals such as Current Science, Engineering Fracture Mechanics, International Journal of Fracture and Journal of the Mechanics and Physics of Solids

Tuesday, Dec 22, 2015, Time: 5:15 PM, Venue: FB 370

 

Gaurav Bhutani, Doctoral student, Imperial College, London

"Modelling three-phase poly-dispersed flows using population balances in an adaptive-mesh finite element framework"

Abstract:

Multi-phase poly-dispersed flows are found extensivley in the inustries such as automative, pharmaceutical, food processing and mineral processing, to name a few. Polydispersity refers to the heterogeneity of the dispersed phase which may exist due to the variation in particle size or any other particle property in space. In this talk, I will be presenting a highly-parallelised open-source finite element framework, called Fluidity, for modeling turbulent industrial-scale polysdispersed flows. Due to the high cpmputational cost associated with these simulations, the dispersed phase is generally considered monosized, but its polydispersed nature can have significant impact on the flow dynamics in many cases. To address this issue, a hybrid finite element -- control volume approach was developed for modelling the macroscale multiphase flow equations coupled to the mesoscale population balance equation. The population balance equation, which models the evolution of the particle size distribution, was implemented in Fluidity as a part of this work and will be discussed in some detail including the solution method. I will also be discussing the application of fully-unstructured, anisotropic mesh adaptivity that led to an excellent improvement in the efficiency of the solution. Model validation results will be presented for a 2-phase bubble column followed by its application to a 3-phase mineral flotation system. In the end, I will also be discussing the potential use of this modelling framework for understanding processes such as erosion and natural hazards including debris flow and snow avalanches.

About the speaker:

Gaurav Bhutani is a final-year Ph.D. student at the Department of Earth Science and Engineering at Imperial College London. He is working towards the modelling of three-phase polydispersed flows for simulating industrial mineral flotation systems at the Rio Tinto Centre for Advanced Mineral Recovery. He completed his B.Tech.-M.Tech. dual degree in Mechanical Engineering in 2007 from Indian Institute of Technology Kanpur. Post that he worked in the industry for 4 years in metal mining and data analytics before returning to academia. He will be defending his thesis in March 2016.

Friday, Dec 11, 2015, Time: 5:15 PM, Venue: FB 370

 

Prof. Fahed Anwer, Mechanical Engineering, ZHCET, AMU

"On the development of Fluid Structure Interaction solver: Handling of moving bodies"

Abstract:

Fluid structure interaction is of great relevance on many fields of engineering as well a in the applied sciences. Hence, the development and application of respective simulation approach has gained great attention over the past decades. Often when interaction effects are essential this comes along with large structural deformations. So, it is of great relevance of being able to adequately deal with this case. Obviously, key points in the simulation of coupled problems are the coupling issues itself. Coupling issues are both the transfer of quantities at the interface and the computational coupling algorithm. In this work, effort is directed towards development of high fidelity coupled solver with which can handle large deformations.
The fluid solvers developed at MED, AMU is interfaced with a solid solver(being developed by colleagues in ME, IIT Kanpur). Resulting combined CSD-CFD code will be tested for variety of problems. The fluid solvers which are used are based on Moving Mesh and Fixed Mesh Methods. Moving Mesh Method based approach utilizes body con-formal mapping while Fixed Mesh method uses Immersed Boundary approach.

About the speaker:

Fahed Anwer obtained his doctorate from Department of Applied Mechanics, IIT, New Delhi in 2006. He was awarded the Best Post graduate project at IIT Delhi in 2006 for his doctoral work. He subsequently completed his post doctorate at Laboratoire d'Informatique pour la Mechanique et les Science de I'Ingenieur, (LIMSI), Paris. Since then he is serving in the Department of Mechanical Engineering, ZHCET, AMU Aligarh as an Assistant Professor. His main areas of interest are Turbulence, Non Oberbeck-Boussinesq flows, Insect Aerodynamics, Fluid Structure Interaction. His research publications have appeared in Journal of Computational Physics, JFM, Physics of FLuid, Computers and Sturctures, Numerical Hat Transfer Part A: Applications, Industrial Engg and Chemistry Research, International Journal of Therm Physics.

Friday, Nov 13, 2015, Time: 5:15 PM, Venue: FB 370

 

Dr. Jeevanjyoti Chakraborty, University of Birmingham

 

"From energy to applications in biology: Modelling the mechanical underpinnigns of lithium-ion batteries and plant roots "

Abstract:

A key determinant of the performance of almost every engineered and natural system is its mechanical behaviour. Efforts to understand and control this bahaviour can reveal commonalities and motivate application in related areas. With that motivation, this talk will take a brief look at microfluidic electro-chemical systems. and then focus on two important systems from energy and biology, namely: lithium-ion batteries and plant root growth.

Lithium-ion batteries are widely used in almost all portable electronic devices and most recently in electric vehicles. However, they can become commerciallly competitive only with much higher energy capacity - something which can be achieved with the use of new electrode materials like silicon. But use of sillicon poses a major problem in that it undergoes huge deformations due to infusion of lithium during charging. The first part of this talk describes a framework to understand the fundamentals of such diffusion-induced large deformations, and investigate the possibility of buckling as a means of mechanical failure of a cylindrical electrode particle. A simple strategy to mitigate such buckling is also examined. Additionally, a multiple-scales based homogenization framework is outlined that upscales the electrode particle-level model to the whole electrode level.

The second part of this talk is concerned with understanding certain mechanical aspects of plant root growth which is not just an attractive frontier of developmental biology but is also important for developing bio-engineered plants that can thrive in adverse climatic and agricultural environments. One of the long-standing interests in plant mechanobiology at the cellular level is to establish a mechanistic interpretation of the orientation of cellulose microfibrils (which primarily dictate the anisotropic growth of cells) embedded in the cell walls. This talk discusses a framework based on a fibre-reinforced viscous fluid model that incorporates a direct dependence of the fibre deposition angle on the principal stress direction. This dependence, based on existing experimental evidence, is found to influence growth in interesting ways.

Finally, a brief overview is presented on how these modelling frameworks may be extended and applied in related topics like supercapacitors and biofuel production.

About the speaker:

Jeevan qualified with a Dual Degree in Mechanical Engineering from IIT Kharagpur in 2009. Immediately after that, he joined the PhD programme at IIT Kharagpur itself working under the supervision of Prof. Suman Chakraborty in the broad area of microfluidics and nanofluidics, particularly on electrokinetic flows through nanoconfinements. He defended his thesis in October, 2013.

From December 2013 to April 2015, he worked as a postdoctoral researcher at the Mathematical Institute in the University of Oxford on modelling lithium-ion batteries.

From April 2015 he is working as a Research Fellow in the University of Birmingham on modelling the mechanical behaviour of plant root growth with applications spanning from food security to energy. In 2014, he was one of five recipients across all engineering disciplines in the country to be awarded the Innovative Student Projects Award at the Doctoral Level from the Indian National Academy of Engineering. With research interests in both fluid and solid mechanics as well as electrochemical transport, he has publications in some reputed journals like Physics of Fluids, International Journal of Solids and Structures, Physical Review E, Electrophoresis, Journal of Power Sources, and Soft Matter.

Wednesday, Nov 04, 2015, Time: 5:15 PM, Venue: FB 370

 

Dr. Atam RAO, Department of Mechanical Engineering, IIT Kanpur

 

"A Simpler and Safer Nuclear Power Plant - The Technology, Design and Economics of the ESBWR"

Abstract:

The seminar will cover the technology and innovation behind the major design features that resulted in the design of a nuclear power plant that probably is the simplest design available globally. This simplification makes it the most economical design while also ensuring enhanced safety using features without reliance on complex power supplies and moving parts. The testing and analysis to qualify and prove the design and safety features involved a multi-year global effort involving universities, national laboratories and industry design team. This is one of the designs selected by India for the planned acceleration of nuclear power during the next decades.

About the speaker:

Dr. Atam RAO was the leader of the international design team that developed the ESBWR. He has a B.Tech from IIT Kanpur and a Ph.D from the University of California, Berkeley in Mechanical Engineering. He worked at General Electric company in San Jose, USA for 31 years on advanced nuclear power plant designs. He also worked 5 years at the international Atomic Energy Agency (a UN agency) in global advanced nuclear plant design programs. He is a fellow of ASME and the recipient of the ASME Westinghouse Gold and Silver Medals for contributions to the Power Industry.

Wednesday, Oct 28, 2015, Time: 5:15 PM, Venue: FB 370

 

Dr. Frederic LEFEVRE, Department of Energy and Environmental Engineering, INSA Lyon, FRANCE

 

"Thermo-hydrodynamics of an Extended Meniscus as Unit-cell Approach of Pulsating Heat Pipe"

Abstract:

This presentation focuses on self-sustained thermally-induced oscillations of a two-phase system consisting of an isolated confined liquid-vapour meniscus(a single liquid plug adjoining a vapour bubble) inside a circular capillary tube. The tube length is exposed to a net temperature gradient, thereby creating a continuous cycle of evaporation and condensation. This system represents the simplest 'unit-cell' version of a Pulsating Heat-Pipe (PHP). The fundamental understanding of the transport behaviour leading to self sustained oscillations is vital for building the hitherto non-existent mathematical models of the completer PHP system. A unique and novel understanding of the system dynamics has been achieved by real-time synchronization of the internal pressure measurement with high-speed videography that was used to visualize and record the meniscus oscillations and the thin liquid film that is laid on the wall when the meniscus leaves the evaporator. Analytical and numerical appraoches are developed to simulate the behaviour of this simple system.

About the speaker:

Prof. Frederic LEFEVRE is the Director of Department of Energy and Environmental Engineering, INSA Lyon, FRANCE. His research interests include energy systems, pulsating heat pipe.

Friday, Oct 16, 2015, Time: 5:15 PM, Venue: FB 370

 

Dr. Nachiketa Tiwary, Department of Mechanical Engineering, IIT Kanpur

 

"The Structure of Stop Consonants"

Abstract: The articulation of stop consonants involves momentary blockage of air in mouthA's oral cavity. Individual pronounciations of these consonants vary markedly with age, gender, accent, emotional state, and cultural background, Yet as listeners we are able to correctly extract the right cues from varying pronunciations of the same consonant, and use them to identify the articulated consonant. Here, we present the fundamental structure underlying each of the stop consonants and also the mathematical interrelationships existing between their individual structures. We show that such structures may be potentailly used as A"recipeA" for artificial synthesis of pure stop consonants. Towards this end, we have chosen to analyze Devanagari alphabet stops We made this choice for two reasons; because this alphabet has a comprehensive and logically organized inventory of stop consonants which is much larger than that found in several other languages, and also because all the stops in this alphabet terminate with the neutral vowel schwa, i.e. A'uA' as in A'sunA'.

While the former reason makes our findings applicable to several world languages, the latter factor helps reduce the analytical complexity of our endeavor. The alphabet contains velar, palatal, retroflex, dental and bilabial stop consonants in five different flavors; voiceless-unaspirated, voiceless-aspirated, voiced-unaspirated, voiced-aspirated, and nasal. Our study demonstrates how additive combinations of a relatively few number of simple acoustics signals can be potentially used to generate the entire non-nasal stop consonant matrix comprising of twenty stos.

About the speaker:

Dr. Nachiketa Tiwary is an Associate Professor in the Departmentof Mechanical Engineering, IIT Kanpur. He received his Ph.D. from Virginia Tech, USA and MBA from Babson College. His research interests include Acoustics ans Noise control, Solid Mechanics, Composite Structures, Vibrations and Product Design.

Monday, Oct 5, 2015, Time: 5:15 PM, Venue: FB 370

 

Dr. Rajendra Patrikar, Department of Electronics, VNIT Nagpur

 

"Low cost Printed Circuit Board based EWOD device for Digital Microfluidics Applications"

Abstract: Digital Microfluidics (DMF) is an emerging liquid-handling technology that enables individual control over droplets on array of electrodes. The applications of Digital Microfluidics are wide encompassing various disciplines, for example Biology and Chemical Engineering, that are still expanding. The most notable of them include portable assays such as DNA, PCR and Proteomics. With Digital Microfluidics, many samples can be created and analyzed in parallel on the same chip this effectively saving time and improving efficiency. Introduction of Optofluids has revolutionized Biomedical Imaging. As the device is on a micro-scale it can capture images of high resolution as well as magnification by integrating the device with imaging electronic circuits. This can be a component of monitoring devices. However, cost is a major concern.

In this talk a low cost approach for development and characterization of open configured electro wetting on dielectric (EWOD) based digital microfluidics devices will be presented. The array of electrodes pattern is realized on copper plated printed circuit board (PCB). Bio-compatible Polydimethylsiloxane (PDMS) is used as dielectric as well as hydrophobic layer which is a competitive substitute of expensive materials like Teflon-AF and Parylene-C. The device is tested by low cost droplet handling characterization system. Contact angle is measured by curve fitting; the volume of a droplet is calculated using a novel approach based on mathematical modelling of droplet as a spherical cap. The droplet transporting and merging are successfully performed on a fabricated device and velocities for forward and reverse direction on square and interdigitated pattern are also measured. The device is also successfully demonstrated for mixing applications using direct statistical methods.

About the speaker:

Dr. Rajendra Patrikar is working presently as Professor of Electronics at VNIT Nagpur at Center of VLSI and Nanotechnology. He has an M.Tech in Electrical Engineering from IIT Bombay. He later joined the Microelectronics Project in the Department of Electrical Engineering at IIT Bombay from where he completed hid Ph.D.(1992). He joined the faculty of IIT Bombay after working for a year at Computer-vision at R&D, Pune. Later he moved to Singapore to work in TECH semiconductor (now, micron) in the Advanced Device Technology Department (1998-2000). After working there for three years he moved to Institute of High Performance computing, Singapore which is a super-computing center, where he initiated work in the area of nano-electronics and worked for three years (2001-2003). He was a Team Leader of a Nanotechnology group at Computational Research Laboratory Pune (Tata group) for one year. He has published about 28 papers in international journals and 70 papers in international refereed conferences and 20 papers in national conferences. He has also filed four patents in the last two years. Earlier he obtained a patent in USA. He is a fellow of IETE, life member of ISSS, senior member of IEEE and member of SPIE. He has obtained project grants from various agencies and he is the coordinator of various projects, including projects sponsored by Ministry of Communication and Information Technology (MCIT), Aeronautical Development Agency (ADA), Board of Research in Nuclear Sciences (BRNS), Rajiv Gandhi Science and Technology center (RGSTC). He is also heading the center for Innovation at VNIT Nagpur.

Friday, Sep 11, 2015, Time: 5:15 PM, Venue: FB 370

 

Dr. Santanu Misra, Department of Earth Sciences, IIT Kanpur

 

"Brittle-ductile Transition during Fault Reactivation : Implications in Earthquake Nucleation"

Abstract: Earthquake nucleation essentially happens during fault reactivation, when accumulated elastic energy is released due to sudden slip along the fault interface. However, not all faults have earthquake generation potential. With the help of natural examples, laboratory experiments and theoretical analysis this presentation will focus on some controlling factors which dictate the nature of fault reactivation

 

About the speaker:

Dr. Santanu Misra is an Assistant Professor in the Department of Earth Sciences, IIT Kanpur. He received his Ph.D from Jadavpur University in 2007. His research interests include Structural Geology and Tectonics, Experimental Rock Deformation and Rock Physics, Deformation Mechanisms & Micro-structure of rocks

Friday, Aug 21, 2015, Time: 5:15 PM, Venue: FB 370

 

Dr. Aakash Rai, Research Engineer in General Electric, Bangalore

 

"Advanced Numerical Models for Assessing Human Exposure to Indoor Contaminants"

Abstract:

It is important that indoor environments (such as buildings and transportation systems) are designed to be healthy and comfortable for human occupancy. A well designed indoor space can enhance occupants' productivity (by 6-9%) and health. To achieve a healthy indoor environment, it is crucial to protect its occupants from various air pollutants such as harmful gases and particles. Ozone is one such indoor air pollutant, and exposure to it is associated with increased morbidity and mortality risks for humans. Ozone is also a major driver of indoor air chemistry, and it reacts with various indoor materials (fragrances, cleaners, carpets, clothing etc.) to generate numerous byproducts. These ozone-generated byproducts include many volatile and semi-volatile organic compounds (VOCs and SVOCs) as well as particles, which can be even more harmful to human health than ozone itself.

This seminar will introduce the development of advanced numerical models for assessing human exposure to ozone-generated particles. I will share experimental results that revealed particle generation from ozone reactions with human-worn clothing. I will focus on the different physical mechanisms that govern the fate of these ozone-generated particles (such as particle nucleation, growth, and deposition); and also explain the development of a numerical model for simulating these mechanisms. By using the model, I will demonstrate that ozone reactions with human-worn clothing could be an important source of ultrafine particles in indoor spaces such as classrooms and airliner cabins, a potential health concern. Finally, I will conclude by highlighting future research opportunities to work towards achieving a healthy indoor environment.

 

About the speaker:

Dr. Aakash Rai is a Research Engineer at the Flow and Thermal Laboratory in General Electric Company at Bangalore. He received his B.Tech. in Mechanical Engineering from IIT Kharagpur in 2008, and then worked for Defence Research and Development Organization (DRDO) as a Scientist for two years. Subsequently, he obtained a Ph.D. in Mechanical Engineering from Purdue University in 2014. His research interests include Indoor Air Quality (IAQ), Computational Fluid Dynamics (CFD), Heat Transfer, and Fluid Flow.

Friday, Aug 17, 2015, Time: 5:15 PM, Venue: FB 370

 

Prof. S. N. Singh, Department of Electrical Engineering, IIT Kanpur

 

"Intelligent System Applications in Solving Engineering Problems"

Abstract:

Due to increased complexity of the systems, cost reduction and detailmodeling of the systems, the requirements of optimization have been increased. The conventional methods, which guarantee to provide the optimal solution, fail to solve many practical problems due to several requirements of these methods. The most familiar conventional optimization techniques fall in two categories viz. calculus based method and enumerative schemes. Though well developed, these techniques possess significant drawbacks. Calculus based optimization generally relies on continuity assumptions and existence of derivatives. Enumerative techniques rely on special convergence properties and auxiliary function evaluation. Moreover, these optimizations are generally single path search and stuck with the local optima.

Intelligent based optimization methods such as genetic algorithm (GA), particle warm optimization (PSO), bacteria foraging, ant colony, neural networks, etc. are multi-path search and provide solution near to the global optima. They do not require derivatives of objective function and constraints. This presentation briefly covers some of the important techniques of optimization along with scope and future challenges

 

About the speaker:

Prof S. N. Singh obtained his M. Tech. and Ph. D. in Electrical Engineering from Indian Institute of Technology Kanpur, in 1989 and 1995, respectively. Presently, he is a Professor in the Department of Electrical Engineering, Indian Institute of Technology Kanpur. Before joining IIT Kanpur as Associate Professor, Dr Singh worked with UP State Electricity Board as Assistant Engineer from 1988 to 1996, with Rookree University (Now IIT Rookree) as Assistant Professor from 1996 to 2001 and with Asian Institute of Technology, Bangkok, Thailand as Assistant Professor from 2001 to 2002. Dr Singh received several awards including Young Engineer Award 2000 of Indian National Academy of Engineering, Khosla Research Award of IIT Roorkee, and Young Engineer Award of CBIP New Delhi (India), 1996. Prof Singh is receipt of Humboldt Fellowship of Germany (2005, 2007) and Otto-monsted Fellowship of Denmark (2009-10). Dr Singh received 2013 IEEE Educational Activities Board Meritorious Award in Continuing Education which is very prestigious award, first time won by a person of R10 region (Asia-Pacific).

His research interests include power system restructuring, FACTS, power system optimization & control, power quality, wind power, etc. Prof Singh is Fellow of INAE, IE(I), IETE(I), IET(UK) and a Senior Member of IEEE (USA). Prof Singh has published more than 370 papers in International/national journals/conferences. He has also written two books one on Electric Power Generation, Transmission and Distribution and second is Basic Electrical Engineering, published by PHI, India.

Monday, Aug 3, 2015, Time: 5:00 PM, Venue: FB 370

 

Dr. Manoj K Harbola, Department of Physics, IIT Kanpur

 

"Introduction to Density Functional Theory (DFT)"

Abstract:

The density functional theory (DFT) is a defacto theory of electronic structure of materials. It became popular because of its ease of handling many electron problem. In this talk we will start from basics of quantum mechanics and introduce many body Schrodinger equation. difficulties associated with solving this equation will be discussed. Finally, we will show how these difficulties are bypassed by DFT.

 

About the speaker:

Prof. Manoj Kumar Harbola joined the Department of Physics, IIT Kanpur in 2000. He obtained his doctoral degree at the City University of New York, USA. Subsequently, he carried out postdoctoral research at the University of North Carolina, Chapel Hill, USA before joining the Center for Advanced Technology, Indore as a Scientist.

His research interests are Electronic Structure of Atoms, Molecules and Solids using Density Functional Methods.

Seminars : Summer 2015

Friday, Jul 10, 2015, Time: 4:15 PM, Venue: FB 370

 

Dr. Sushma Santapuri, Polytechnic University of Puerto Rico


"Unified Continuum Modeling of Thermo-Electro-Magneto-Mechanical Behavior with Application to Multifunctional Materials and Structures"

Abstract:

Multifunctional materials are intelligent material systems designed to exhibit multiple functionalities (e.g. sensing, self-healing, energy harvesting etc.) in addition to load-carrying capacity. These materials are currently implemented in various applications ranging from aerospace, infrastructural, automotive, to biomedical. However, design of such advanced material systems is often limited by the lack of mathematical models that can accommodate their inherent nonlinearity, inhomogeneity, and multiscale, multiphysical effects. To enable the design of the next-generation of intelligent structures with enhanced capabilities and expanded performance space, improved mathematical modeling frameworks are needed that can accommodate these effects. In this talk, I will be presenting my research on development of such advanced mathematical models and computational tools for design and analysis of novel multifunctional composite structures. The talk will focus on two different aspects of material modeling: (i) development of a first-principles based framework for characterization of fully coupled thermo-electro-magneto-mechanical material behavior, and (ii) a mathematical approach to formulate leading-order models for complex multifunctional systems with coupled thermomechanical and electromagnetic behavior. An application to this generalized framework will be demonstrated through a case study on a smart composite actuator consisting of embedded magnetostrictive material in a non-magnetic metallic matrix. The scope of methodologies presented in this talk extends beyond the case study presented, and motivates various future research directions.

About the speaker:

Dr. Sushma Santapuri is a tenure-track faculty member in Mechanical Engineering at Polytechnic University of Puerto Rico. She has previously worked as a postdoctoral researcher at The Ohio State University in Smart Materials and Structures lab. She obtained her PhD and B.Tech in Mechanical Engineering, from Ohio State University (2012) and Indian Institute of Technology - Chennai (2007), respectively. Her areas of expertise and research interests include continuum mechanics, multiphysics modeling of advanced materials, composite smart structures, and multifunctional material systems. Her work has resulted in 5 journal publications and conference proceedings, a text-book chapter, with several others publications under review. She is also the recipient of NSF EPSCoR faculty start-up award.

Monday, June 9, 2015, Time: 11:00 AM, Venue: FB 370


Dr. Vaibhav Agrawal, Carnegie Mellon University


"A Dynamic Phase-field Model for Structural Phase Transformations: Prescribable Complex Kinetics and Nucleation with Diffuse Interfaces"

Abstract:

The motion of microstructural interfaces is important in modelling twinning and structural phase transformations. In continuum setting nonconvex strain energy density functions have been used to model these transformations. Non-convex energy along with linear momentum balance results in non-unique solutions, so a kinetic law for the interfaces and a nucleation criterion is required to resolve the non-uniqueness. However, in this approach the interfaces are "sharp", i.e, deformation gradient is discontinuous across the interface. The computational implementation with sharp interfaces using level-sets or tracking is challenging and/or expensive, particularly when there are multiple interfaces as in problems of interest. Other approaches such as phase-field or augmenting the stress response with a viscosity and strain gradient term have smoothed out interfaces and do not require tracking of interfaces; however, these are severely constrained in the kinetics and nucleation criteria that can be imposed.

We present the formulation of a phase-field model – i.e., a model with regularized interfaces that do not require explicit numerical tracking – that allows for easy and transparent prescription of complex interface kinetics and nucleation. The key ingredients are a re-parametrization of the energy density to clearly separate nucleation from kinetics; and an evolution law that comes from a conservation statement for interfaces. This enables clear prescription of nucleation – through the source term of the conservation law – and kinetics– through a distinct interfacial velocity field. We describe the characterization of the method in 1D and 2D, and apply it to a number of model problems involving dynamic twinning interfaces.


Reference:

A Dynamic Phase-field Model for Structural Transformations and Twinning: Regularized Interfaces with Transparent Prescription of Complex Kinetics and Nucleation. Part I: Formulation and One-Dimensional Characterization. (accepted in JMPS)

A Dynamic Phase-field Model for Structural Transformations and Twinning: Regularized Interfaces with Transparent Prescription of Complex Kinetics and Nucleation. Part II: Two-Dimensional Characterization and Boundary Kinetics. (accepted in JMPS)

Seminars : Spring 2014-15

Monday, April 13, 2015, Time: 5:15 PM, Venue: FB 370


Dr. Basant L. Sharma, Assistant Professor Department of Mechanical Engineering, IIT Kanpur


"Scattering of waves by line defects on two dimensional lattices"

Abstract:

The talk concerns some recent work on scattering of (scalar) waves in three types of lattices (square, triangular, hexagonal) by a (finite or semi-infinite) line defect (i.e., a rigid constraint or a crack). Exact solutions are provided, in integral form, for the semi-infinite case of both types of defects. Rigorous statements are provided for the approximation of finite case by its semi-infinite counterpart, along with the existence and uniqueness of the latter in a suitable space. The far field approximations, as well as exact near tip fields, are provided in closed form for the semi-infinite defects. The continuum limit of semi-infinite case for all six problems coincides with the classical Sommerfeld diffraction problem via convergence in suitable Sobolev space. Potential applications of the results are: wave scattering by sharp edged defects in meta-materials, high-frequency elastic wave scattering in elastic media, numerical solution of scattering of plane polarized E/M waves by conducting screens/edges, acoustic wave scattering by soft or hard screens/edges, etc, besides the mechanical application in context.


About the speaker:

Dr. Sharma obtained B. Tech. degree in Mechanical Engineering from IIT Bombay and PhD in Mechanics from Cornell University. After this he served as Post-doctoral research fellow at Cornell University and Ecole Polytechnique, France. He joined the department of Mechanical Engineering of IIT Kanpur in January 2007. His research interest involves theoretical problems in mechanics as well as applied mathematics. In particular Dr. Sharma's research is centered around the mechanics of crystals and involves a theoretical study of equilibrium and motion of defects such as dislocation, martensitic phase boundary, and crack.

Wednesday, April 8, 2015, Time: 5:15 PM, Venue: FB 370


Dr. S. M. Abbas, Joint Director DMSRDE, DRDO, Kanpur


"Role of DRDO in Nation Building"

Abstract:

DRDO was formed in 1958 from the amalgamation of the then already functioning Technical Development Establishment (TDEs) of the Indian Army and the Directorate of Technical Development & Production (DTDP) with the Defence Science Organization (DSO). Today, DRDO is having more than 50 labs, engaged in developing Defence Technologies covering various disciplines like aeronautics, armaments, electronics, combat vehicles, engineering systems, instrumentation, missiles, advanced computing and simulation, special materials, naval systems, life sciences, training, information systems and agriculture. DRDO is backed by over 5000 scientists and about 25,000 other scientific, technical and supporting personnel. The Department's core business is to design, develop and lead to production of state-of-the-art weapon systems & sensors for the Indian defence forces. The Department offers opportunity to the stakeholders/clients to participate through different forums in the activities of the Department. Stakeholders continuously participate in the monitoring of the projects/programmes of their interest with their viewpoints, apprehensions, reservations, etc. These are objectively discussed and addressed as the project/ programme progresses. The committees and boards are project/ programme specific, suitably structured and are convened at a mandated periodicity. Thus, all the concerns of the stakeholders/clients are addressed objectively and timely in an institutionalized manner. For general interactions with the Services, the Department's Head Quarter has a Directorate of Interaction with Services for Business. Apart from this DRDO also supports research sponsored in academic institutions under extramural research (ER) scheme and through MoU between DRDO laboratories and academia for mutual benefits in the interest of defence preparedness and in nation building. In this talk I will try to put the over view picture of DRDO, its achievement and the types of work being pursued in DMSRDE. Further, the talk will also highlight on how can IIT K and DMSRDE together help in strengthening the nation.


About the speaker:

Dr. S. M. Abbas is presently Scientist 'F', Joint Director and head of Central Analytical Facilities in Defence Materials and Stores Research & Development Establishment (DMSRDE), Kanpur, India. He did his M. Tech. in Metallurgical Engg.& Materials Science from IIT Bombay in 1997 and PhD in Physics (Solid state materials) from IIT Delhi in 2007.His area of interest is characterization of materials, development of camouflage materials/ products, Radar absorbing and multi-spectral Camouflage Net, Mobile Camouflage System, and Radar absorbing structural Composites. He has published 12 papers in reputed journals and presented 10 papers in International conferences. He has also received DRDO award 1999 for development of thermal pads.

Wednesday, March 25, 2015, Time: 5:15 PM, Venue: Video Conferencing Room, Outreach Building, IITK


Dr. Pritam Chakraborty, Computational Materials Scientist Idaho National Laboratory, USA.


"Novel High Temperature Heat Transfer Fluid for Concentrating Solar Power Scheme"

Abstract:

The fatigue life and number of cycles to crack nucleation in Ti-alloys exhibit considerable variation. The underlying microstructure has been observed to have significant influence on the scatter and needs consideration for accurate life prediction of these alloys. Such microstructure dependent modeling can provide safe operational limits, optimal design safety factors and prevent premature retirement of components from service. The strong elasto-plastic anisotropy of Ti-alloys cause significant load shedding induced stress concentration near grain boundaries and is perceived to be the primary driver of microstructure-dependent crack nucleation. Though crystal plasticity based finite element method (CPFEM) is fairly successful in capturing these localized stress concentrations, it requires very small time steps for stable numerical integration. Hence, CPFEM based fatigue simulations for large number of cycles till crack nucleation becomes computationally prohibitive. To alleviate this issue, a wavelet based multi-time scale method was developed, motivated from the dual-time scale evolution of CPFE variables under cyclic loading. A transformation of the CPFE variables to the wavelet space then enabled decoupling and integration in the coarse time-scale with much larger time steps. With the use of this multi-time scale algorithm, huge computational savings were obtained with fairly accurate solutions. A non-local crack nucleation criterion based on the Stroh model was then utilized to predict the cycles to crack initiation. Subsequently, correlations between the microstructural descriptors, load forms and cycles to crack nucleation were developed to provide engineering scale predictions of fatigue life.


About the speaker:

Pritam Chakraborty is a computational materials scientist at Idaho National Laboratory, USA. He has done his Bachelor's in Mechanical Engineering from Jadavpur University, followed by a Master's from IIT Kanpur. After working as a mechanical engineer at GE Global Research Center at Bangalore for couple of years, he joined the PhD program at The Ohio State Univeristy, USA. He completed his PhD in 2011following which he moved into his current role. His research interest is the area of computational solid mechanics with focus on meso-scale model and multi-scale method development to study fatigue, fracture, plasticity and creep in metals and ceramics. His recent research activities include development of (i) non-local damage model to study microstructure dependent intergranular brittle fracture in UO2;(ii) engineering scale model calibration and pellet fracture studies; (iii) crystal plasticity model to capture irradiation induced localization in BCC iron; (iv) phase-field model for microstructure evolution under elastic and plastic driving force (e.g. grain growth); (v) phase-field based creep model for polycrystalline materials considering lattice site generation/annihilation.

Monday, March 23, 2015, Time: 5:15 PM, Venue: ME Conference Room


Dr. Nitin Gupta, Assistant Professor Department of Biological Sciences and Bioengineering, IIT Kanpur


"Exploring neural mechanisms of sensory perception using the insect brain"

Abstract:

The remarkable capabilities organized by the brain — from seeing to singing, from remembering to running — originate in the electrical activities of neurons. Neurons interact with each other forming circuits, which process sensory information and drive appropriate behaviors. The basic organizing principles of neural circuits have been conserved during the course of evolution. My research is focused on understanding the fundamental mechanisms used by neural circuits for processing information. The insect olfactory system (sense of smell) provides a good model system because of its simple organization, rich behavior, and amenability to in-vivo experiments. In this talk, I will describe some recent work using this system and the tools of electrophysiology, imaging, and simulations for studying circuit properties, such as inhibition and oscillatory synchronization. I will also describe experiments testing whether the precise timing of neural activity, at the scale of tens of milliseconds, carries usable information in the responses of relatively quiet neurons. I will end the talk by discussing my interest in understanding the processing of ecologically relevant smells by the mosquito brain.


About the speaker:

Dr. Nitin Gupta graduated from IIT Kanpur in 2004 with a B. Tech. in computer science and an interest in biology. He then joined the PhD program in bioinformatics and systems biology at the University of California, San Diego. His thesis focused on developing computational tools for data analysis in protein mass spectrometry, and using these tools for high-throughput annotation of genes and proteins. A collaborative project on identification of neuropeptides introduced him to the field of neuroscience. After completing his PhD in 2009, Nitin spent a few months in the department of Psychology, and then moved to the National Institutes of Health to learn the techniques of experimental neuroscience. He joined the department of Biological Sciences and Bioengineering at IIT Kanpur as an Assistant Professor in July 2014.

Wednesday, March 18, 2015, Time: 5:15 PM, Venue: ME Conference Room


Dr. Sachin Y. Shinde, Post-Doctoral Fellow, Engineering Mechanics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore.


"Unsteady actuator disk type action in the 'orderly' jet induced by a chord wise flexible foil flapping in the absence of free stream"

Abstract:

Thrust generation is an essential component of all flying and swimming animals and vehicles. Flapping mode of propulsion has been successfully exploited by birds, insects and fish. Force generation by flapping wings and fins in nature thus has been a major source of inspiration to study oscillating foils. Many of the wings and fins are flexible, and flexibility, through the intricately coupled solid-fluid interactions between the structure and the fluid, seems to be an important property that makes large changes in the flow, thrust produced and efficiency. Inspired by this, we experimentally investigate the flow induced by the interaction between a flapping flexible surface and the surrounding fluid for one extreme end of flight regime (zero free-stream speed), i.e. the limiting case of Strouhal number St -> ∞, a case relevant to hovering. The surface selected for this purpose is a two-dimensional sinusoidally pitching rigid NACA0015 foil to which is attached at the trailing edge a thin flexible flap. First, I will talk about how the flexibility in flapping foil suppresses the jet meandering, a phenomenon encountered by the thrust-generating flapping foils at high Strouhal numbers, for the limiting case of infinite St. It will be shown that only for 'moderately flexible' flaps, a coherent, 'orderly' reverse Benard-Karman vortex jet is obtained. Further, I will present a detailed analysis of the processes of flow generation and thrust production. I will discuss about the role of flexibility in the flow and the vortex generation mechanisms. Thrust generation mainly occurs during some parts of the cycle, and we suggest that it can be modelled as an 'unsteady actuator disk'. (Actuator disk is a thin disk which accelerates the fluid passing through it by adding momentum and energy to the fluid). Flexibility is found to be important in accelerating the near-wake flow and in transferring momentum and energy to the fluid. We show that the deformations of the flexible flap are the ones which are responsible for the generation of favourable pressure gradient along the jet direction, and for the observed actuator disk type action. Using control volume analysis we present a detailed account of when and where the momentum and energy are added to the fluid by the flexible flap. The flap is usefully divided into 'active' and 'passive' portions. It is the active portion that does work on the fluid and adds momentum to it, whereas the passive portion is found to be crucial in determining the location of vortex shedding. Modeling thrust generation as a pulsed actuator disk for hovering insects has been suggested, however, for the flapping foils, the unsteady actuator disk action is being suggested, perhaps for the first time.


About the speaker:

I am currently working as Post-Doctoral Fellow at the Engineering Mechanics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore. Prior to that I have completed PhD as well as M.Sc.(Engg.) from the Department of Mechanical Engineering, Indian Institute of Science (IISc), Bangalore, and B.E. in Mechanical Engineering from the Walchand College of Engineering, Sangli, Maharashtra. I have also worked with Philips India Ltd. My research interests are in the field of experimental fluid dynamics, bio-fluid dynamics (in particular, swimming, flying, fluid-flexible surface interactions), turbulent flows and atmospheric cloud-like flows.

Monday, March 16, 2015, Time: 5:15 PM, Venue: Video Conferencing Room, Outreach Building, IITK


Dr. Vinod Kumar, Associate Professor, Department of Mechanical Engineering, University of Texas at El Paso


"Novel High Temperature Heat Transfer Fluid for Concentrating Solar Power Scheme"

Abstract:

Molten salts are widely used in as the heat transfer fluid (HTF) and thermal energy storage (TES) in a Concentrating Solar Power (CSP) scheme. However, one of the major challenges with molten salt and similar salt mixtures is that they degrade at high temperature. Hence they become unsuitable for CSP operations at high temperature where electricity generated from CSP plant is expected to be cost-competitive to the electricity production from other conventional sources. In this talk, the presenter will discuss a novel compatible high temperature HTF medium possessing high effective heat capacity and thermal conductive. Results from multiphase computational fluid dynamic (CFD) simulation based on solid particle receiver will also be presented to analyze the over-all efficiency of the idea CSP system.


About the speaker:

Dr. Vinod Kumar holds a PhD degree in Mechanical Engineering (ME) (2005, Rice University, Houston, TX, USA) and a Bachelor of Technology (B. Tech. ) degree in Aerospace Engineering (1997, IIT K). He has two years of postdoctoral experience at Rice University, where he developed a high performance computing of space plasma physics. After that, he worked as a senior researcher at the Geophysical Fluid Dynamics Laboratory, Princeton University where his responsibilities included developing HPC computer codes for geophysical fluid dynamic and examining the bottlenecks on scalability and performance through code profiling. Dr. Kumar's current research focus is to develop high fidelity computational thermal-fluid models that are able resolve physics occurring at various temporal and spatial scales, with a particular emphasis on renewable energy systems.

Wednesday, March 11, 2015, Time: 5:15 PM, Venue: Video Conferencing Room, Outreach Building, IITK


Dr. Sushma Santapuri, Associate Professor, Department of Mechanical Engineering, Polytechnic University of Puerto Rico


"Unified Continuum Modeling of Thermo-Electro-Magneto-Mechanical Behavior with Application to Multifunctional Materials and Structures"

Abstract:

Multifunctional materials are intelligent material systems designed to exhibit multiple functionalities (e.g. sensing, self-healing, energy harvesting etc.) in addition to load-carrying capacity. These materials are currently implemented in various applications ranging from aerospace, infrastructural, automotive, to biomedical. However, design of such advanced material systems is often limited by the lack of mathematical models that can accommodate their inherent nonlinearity, inhomogeneity, and multiscale, multiphysical effects. To enable the design of the next-generation of intelligent structures with enhanced capabilities and expanded performance space, improved mathematical modeling frameworks are needed that can accommodate these effects. In this talk, I will be presenting my research on development of such advanced mathematical models and computational tools for design and analysis of novel multifunctional composite structures. The talk will focus on two different aspects of material modeling: (i) development of a first-principles based framework for characterization of fully coupled thermo-electro-magneto-mechanical material behavior, and (ii) a mathematical approach to formulate leading-order models for complex multifunctional systems with coupled thermomechanicaland electromagnetic behavior. An application to this generalized framework will be demonstrated through a case study on a smart composite actuator consisting of embedded magnetostrictive material in a non-magnetic metallic matrix. The scope of methodologies presented in this talk extends beyond the case study presented, and motivates various future research directions.


About the speaker:

Dr. Sushma Santapuri is a tenure-track faculty member in Mechanical Engineering at Polytechnic University of Puerto Rico. She has previously worked as a postdoctoral researcher at The Ohio State University in Smart Materials and Structures lab. She obtained her PhD and B. Tech. in Mechanical Engineering, from Ohio State University (2012) and Indian Institute of Technology - Chennai (2007), respectively. Her areas of expertise and research interests include continuum mechanics, multiphysics modeling of advanced materials, composite smart structures, and multifunctional material systems. Her work has resulted in 5 journal publications and conference proceedings, a text-book chapter, with several others publications under review.

Wednesday, Feb 25 2015, Time: 5:15 PM, Venue: ME Conference Room


Dr. Mohit Law, Fraunhofer IWU, Germany


"Modelling and Control of Machine Tool Structural Dynamics: Progress and Prospects"

Abstract:

Structural deformations of machine tool components interact with the cutting process and the control loop of drives to fundamentally limit performance of machine tools. These structural deformations result in a lack of dynamic stiffness at the tool center point that lead to unstable regenerative chatter vibrations and further limit drive positioning speed and accuracy. The chatter vibrations are further influenced by the changing structural dynamics of the machine as the tool moves along the tool path, resulting in position-varying machining stability of the system.Virtually characterizing these interactions has become necessary to address the need for first-time right high performance machining solutions. This talk presents an overview of my research efforts on modelling and control of process-machine and control-structure interactions. Modelling approaches based the dynamic substructuring approach form the central theme of this talk. Work on active vibration isolation of machine tools using novel electro-hydraulic actuators will also be discussed. Recent work on development of dynamic substructuring frameworks to assist in situ machining of large parts using novel nimble parallel kinematic mobile machine tools will also be explored. The talk will conclude by discussing emerging areas of research in dynamic substructuring and control of machine tools.


About the speaker:

Dr. Mohit Law is a Research Associate at the Fraunhofer Institute of Machine Tools and Forming Technology IWU, Germany. He received his PhD in Mechanical Engineering from The University of British Columbia, Canada in 2013, his Master's from Michigan Technological University, USA in 2008 and his Bachelors' degree from the University of Pune, India in 2003. Mohit has previously worked as a machine tool design engineer in India. His research interests are centered on applying principles of dynamics to a wide range of problems in the machine tool, cutting tool, automotive and aerospace industries. His research has appeared in the ASME Journal of Manufacturing Science and Engineering, the International Journal of Machine Tools and Manufacture, the CIRP-Annals and in the Journal of Multi-body dynamics. He has participated and presented his research in several international conferences. His work has been funded by the Canadian Network for Research and Innovation in Machining Technology and the Fraunhofer Gesellschaft's ICON Project on Production Engineering Research for Wind Energy.

Friday, Feb 20, 2015, Time: 5:15 PM, Venue: Video Conferencing Room, Out Reach Building, IITK


Dr. Venkatesh Vijayaraghvan, Advanced Technologist, Manufacturing and Repair Technologies Division Rolls-Royce Aerospace Pte Ltd. Singapore


"COMPUTATIONAL MECHANICS STUDY OF CARBON NANOTUBES AND ITS INTERACTIONS WITH WATER"

Abstract:

Recent discoveries of various forms of nano-materials have stimulated research on their applications in diverse fields. Of particular mention is the carbon nanotubes (CNTs) whose unique mechanical and physical properties have triggered a wide-spread research interest. The major focus of this thesis is to study and understand the mechanical properties of free form CNTs and CNTs interacting with water molecules by employing molecular dynamics (MD) simulation. At the beginning, MD simulations were performed on free form SWCNTs and SWCNT array to gain better understanding on the mechanical properties of CNT. The mechanical properties of single-walled CNTs (SWCNTs) interacting with water molecules were then studied by subjecting the SWCNT to four forms of mechanical loading conditions ¬– compression, tension, torsion and shear. The results indicate that the mechanical performance of SWCNT is strongly affected due to interaction of the surrounding water molecules. In addition, the influence of the SWCNT geometry on the mechanical properties of water submerged SWCNTs is also examined. Another study involved the transport characteristics of water molecules in CNTs using MD simulation. The effect of channel diameter, defects and the inter-layer spacing on the transport of water molecules was studied by subjecting the flow of water molecules through CNTs under pressure. The findings show that the efficiency of water transport can be improved by deploying bigger SWCNTs that have wide channel diameter. The investigations and conclusions obtained from this project is expected to further compliment the potential applications of CNTs as promising candidates for applications in nano-fluidics and NEMS devices.


About the speaker:

Dr. Venkatesh is working as Advanced Technologist (Manufacturing and Repair Technologies Division) with Rolls-Royce Aerospace Pte Ltd, Singapore. He obtained his PhD from the School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore in 2014. Prior to that he obtained his Master's degree in Mechanical Engineering from National University of Singapore in the year 2009 and Bachelor's degree in Production Engineering from Anna University, MIT Campus in the year 2006. He has published so far 25 peer reviewed SCI journal publications in the field of computational mechanics and manufacturing engineering.

Wednesday, Feb 18, 2015, Time: 5:15 PM, Venue: ME Conference Room


Dr. Akhil Garg, Research Fellow, School of Civil and Environmental Engineering, NTU, Singapore


"Modelling of Manufacturing Processes by a Computational Intelligence Approach"

Abstract:

Modelling is a term widely used in System Identification (SI), which is referred to as the art and science of building mathematical models of systems using some measured data. The systems of interest in this work are additive manufacturing processes such as fused deposition modelling, machining processes such as turning, and finishing processes such as vibratory finishing. These processes comprise multiple input and output variables, making their operating mechanisms complex. In addition, it can be costly to obtain the process data and therefore there is a strong need for effective and efficient ways of modelling these systems. The models formulated must not only predict the values of output variables accurately on the testing samples but should also be able to capture the dynamics of the systems. This is known as a generalization problem in modelling. The generalization of data obtained from manufacturing systems is a capability highly demanded by the industry. Past studies reveals that an advanced computational intelligence (CI) approach of multi-gene genetic programming (MGGP) is a possible alternative because it can produce explicit functional relationships between process parameters without the need of assuming any pre-defined structure of a model and other statistical assumptions. However, MGGP have not been able to gain full prominence because it tends to produce over-fitting models. In the present work, four variants/methods of MGGP are proposed to counter the four shortcomings identified, namely (1) inappropriate procedure of formulation of the MGGP model, (2) inappropriate complexity measure of the MGGP model, (3) difficulty in model selection, and (4) ensuring greater trustworthiness of prediction ability of the model on unseen samples. A robust CI approach was also developed by applying these four variants of MGGP and the M5ʹ method in parallel. The statistical comparison with other methods such as MGGP, support vector regression and artificial neural network reveals that the generalization ability achieved from the four variants of MGGP and robust CI approach is better than those of the other methods. Furthermore, the manufacturing processes were optimized using Genetic algorithms and monte-carlo technique by taking into account the uncertainties in the proposed models and input parameters.


About the speaker:

Dr. Akhil Garg completed his PhD from School of Mechanical and Aerospace Engineering, Nanyang Technological University (NTU), Singaporein 2015. His research interests include green manufacturing, robust multi-objective optimization of manufacturing processes, developing ensemble methods for studying manufacturing processes, genetic programming, etc. Prior to this, He received Bachelor's degree (B. Tech.) in Mechanical Engineering from National Institute of Technology (NIT), Rourkela, in 2010. Currently he is working as a Research fellow on "Evaluation of Environmental impacts in Manufacturing processes" from School of Civil and Environmental Engineering at NTU.

Monday, Feb 16, 2015, Time: 5:15 PM, Venue: ME Conference Room


Dr. Vaibhav Sinha, Guest Researcher, Department of Nuclear Engineering, Missouri University of Science & Technology, USA


"Novel Radiation Detection, Instrumentation and Imaging Technologies for Advanced Research"

Abstract:

Novel radiation detection, instrumentation, and imaging technologies play a crucial role in nuclear industry, medical research, and engineering applications as all of these areas utilize radiation technology. A novel imaging system combining traditional neutron and X-ray computed tomography (NXCT) has been designed and developed. This is the first such imaging platform and synthesis method to be developed. The system provides promising results in detection of materials through non-destructive analysis where materials with similar atomic numbers but differing neutron cross sections or vice versa may be present within an object. Normally, interactions of neutrons and X-ray photons with matter produce differing characteristic information that may result in distinctly different visual images. The NXCT system utilizes neutron and X-ray imaging simultaneously without obstructing the beam geometry for each imaging mechanism, and could possibly produce more comprehensive images of the structural and compositional data for a desired object. Based on current studies, it could be concluded that the concept of NXCT can be useful for concealed material detection, material characterization, investigation of complex imaging for in situ studies. In this context, it is imperative to characterize the newly developed digital imaging system as well as describe the parameters associated with performance evaluation. The preliminary evaluation of the NXCT system was performed in terms of image uniformity, linearity and spatial resolution. Additionally, the correlation between the applied beam intensity, the resulting image quality, and the system sensitivity was investigated. The performance of a combined neutron/X-ray combined computed tomography system was evaluated in terms of modulation transfer function (MTF), noise power spectrum (NPS) and detective quantum efficiency (DQE). This presentation will provide an overview of the design, operation, performance analysis and experimental results of the NXCT system. Further more, the second part of the talk will provide a brief description of Cu-67 radioisotope production utilizing photon activation technique, and development of anthropomorphic phantoms for calibrating mobile and whole body counters.


About the speaker:

Dr. Vaibhav Sinha is a Guest Researcher at the Department of Nuclear Engineering at the Missouri University of Science & Technology. He holds a PhD from Missouri University of Science & Technology (2013), an MS from Aachen University of Applied Sciences, Germany (2006), and a BEng (2002) from Agra University, India. He has over 10 years of professional experience in research and teaching. His previous positions include Assistant Professor, Instructor, Research Assistant and Graduate Engineer. His recent research establishes a novel neutron/X-ray combined computed tomography system for advanced nondestructive evaluation research. He also performed research with Research Center Juelich, Germany for development of calibration phantoms for whole body counters, and at Idaho Accelerator Center, USA for production of radioisotope copper-67 using a linear electron accelerator. He has corporate experiences with the aeronautics and power plant industry. His research is based on development of innovative radiation detection and measurement techniques, radiation dosimetry, explosive detection, homeland security applications, nuclear security, development of new algorithms for radiation imaging systems and its performance evaluation, and development of high resolution neutron/X-ray computed tomography system for industrial and medical applications. Dr. Sinha has been honored by Council of Ionizing Radiation Measurements and Standards, American Society for Nondestructive Testing and Alpha Nu Sigma Nuclear Engineering Honor Society. The results of his research include over 27 articles in refereed journals, conference proceedings, and technical presentations.

Monday, Feb 09, 2015, Time: 5:15 PM, Venue: ME Conference Room


Dr. T. Muthukumar, Department of Mathematics, IIT Kanpur


"Homogenization: Principle of Fictitious Material"

Abstract:

The theory of homogenization of partial differential equations is a concept that deals with the study of features that are different at different length scales. For instance, in material science, homogenization deals with the study of the macroscopic behaviour of a composite medium through its microscopic properties. The physical parameters such as conductivity, elasticity etc. are rapidly oscillating between different values across a small length scale. The origin of the word"homogenization" is related to the question of replacing a heterogeneous medium by a fictitious homogeneous one (the 'homogenized' material) for computational purposes. The talk will, for the most part, survey through existing homogenization methods applied to various types of equation and the difficulties therein. The theory of homogenization of partial differential equations is a concept that deals with the study of features that are different at different length scales. For instance, in material science, homogenization deals with the study of the macroscopic behaviour of a composite medium through its microscopic properties. The physical parameters such as conductivity, elasticity etc. are rapidly oscillating between different values across a small length scale. The origin of the word "homogenization" is related to the question of replacing a heterogeneous medium by a fictitious homogeneous one (the 'homogenized' material) for computational purposes. The talk will, for the most part, survey through existing homogenization methods applied to various types of equation and the difficulties therein.

Monday, Feb 02, 2015,Time: 5:15 PM, Venue: ME Conference Room


Prof. S. N. Tripathi,Civil Engineering Department,IIT Kanpur


"Interactions between light and dust-carbonaceous mixture aerosols"

Abstract:

Absorbing aerosol system poses the greatest challenge to our ability to accurately predict climate change. In this talk, I will start by providing a brief background of Mie theory that deals with light-sphere interactions. The limitations of Mie theory in the context of highly complex objects, specifically having size greater than the wavelength of light will be underlined. A few applications of advanced method such as Discrete Dipole Approximation in absorption estimation of dust-carbonaceous aerosols will be discussed. Carbonaceous aerosol absorption is a complex problem because of mixing state-physically separated, homogeneous mixture or core-shell configuration-of aerosols, and poorly characterized absorption spectra of organic aerosols. I will present some latest experimental results on mixing state and optical constants of carbonaceous aerosols. Our results show large scale absorption from organic aerosols in the Indo-Gangetic Plain, which was not considered in earlier global modeling studies. Based on these new observations, earth's radiative budget can be calculated more accurately. Implications to long term changes in Indian summer rainfall, and discoloration of heritage monuments will be discussed.


About the speaker:

Prof. Sachchida Nand Tripathi obtained his PhD from Reading University and was a Post Doctoral Research Fellow at Bhabha Atomic Research Center and Oxford University. He currently holds professor position in Civil Engineering Department and is an adjunct professor in Earth Sciences at IIT Kanpur. He has been a Senior Fellow at NASA Goddard Space Flight Center. He obtained his B. Tech. in Civil Engineering from IIT-BHU (Formerly IT-BHU). Prof. Tripathi has been awarded NASI-SCOPUS young scientist award-2009 in Earth Sciences and Shanti Swarup Bhatnagar Award 2014 in Earth, Atmosphere, Ocean and Planetary Sciences. His research interests are aerosol optics and cloud forming properties, aerosol-rainfall interactions and climate mitigation.

Monday, Jan 19, 2015, Time: 5:15 PM, Venue: ME Conference Room


Dr. Obaidurrahman K., Nuclear Safety Analysis Division, Atomic Energy Regulatory Board (AERB), Mumbai


"Spatial Xenon Oscillations"

Abstract:

Large thermal reactors have remained the main stay of nuclear energy during last five decades. Excellent safety records and reliable operation of thousands of reactor-years has made these reactors a default choice for future nuclear plants. Large core dimensions in terms of neutron migration length, makes these systems spatially unstable against xenon instability. These spatial oscillations, if not controlled properly may lead to slow cycling of local power densities which, may go unnoticed as total core power may not change in course of time. Overall effect could be thermal cycling of fuel and core structural elements and consequent fuel failure. This phenomenon has been extensively studied and spatial control procedure have been well established. Therefore xenon oscillations pose no practical difficulty in safe and smooth operation of present age nuclear power plants. Scaling up of core dimension, a design initiative to gain economy of scale in new generation reactors has rendered renewed topicality to this instability. Seminar will cover the modelling, characterization and control aspects of spatial xenon oscillations in large power reactors. Spatial oscillations and control aspects of advanced reactors will be presented.


About the speaker:

Dr. Obaidurrahman K., is working in Nuclear Safety Analysis Division of Atomic Energy Regulatory Board (AERB), Mumbai. He is involved in development and validation of core dynamics models for safety analysis of Indian power reactors at AERB. He has played a central role in development of AERB 3D kinetics code 'TRIKIN', which a very useful computational tool for carrying out transient simulation of different types of reactors. His analytical findings have provided important technical input towards safety review of several Indian nuclear power plants. He is a recipient of Homi Bhabha Gold medal (2007) and Atomic Energy Young Scientist Award (2013).

Tuesday, Jan 13, 2015, Time: 5:15 PM, Venue: ME Conference Room


Dr. Prashant Saxena, Post-doctoral Research Fellow, Centre for Integrative Genomics, University of Lausanne, Switzerland


"A continuum theory of magneto-mechanics with application to magneto-rheological elastomers"

Abstract:

The nonlinear theory describing electro-mechanical and magneto-mechanical coupling has received considerable attention in recent years. The chief reason is the recent development of electro-rheological and magneto-rheological elastomers (MREs) which are useful in several engineering applications such as sensors and actuators. MREs are polymeric materials in which micron-sized iron particles are dispersed. On the application of a magnetic field, the interaction between these iron particles manifests itself as changes in shape/stiffness at the macroscopic level. In this talk, I will present a nonlinear continuum theory to describe the magnetomechanical coupling in MREs. The recently developed theory of magneto-mechanics, due to the work of Dorfmann and Ogden, is based on the framework of nonlinear elasticity. The magnetic body force is accounted through a so-called 'total energy density' which allows for simple formulations. Furthermore, I will present some recent results towards modelling of rate-dependent mechanisms that lead to energy dissipation in these polymers. This is based on a theory of internal variables in which the dissipation mechanisms are quantified through a multiplicative decomposition of the deformation gradient and an additive decomposition of the magnetic variable. The evolution laws for internal variables and the energy density functions are designed in a way to be consistent with experimental observations as well as with the laws of thermodynamics.


About the speaker:

Dr. Prashant Saxena obtained Master and Bachelor of Technology in Mechanical Engineering from IIT Kanpur in 2009. Later in 2012 he was awarded PhD in Applied Mathematics by Univeristy of Glasgow, UK. Subsequent to this he was a post-doctoral research associate at University of Erlangen-Nuremberg, Germany for two years and then moved to University of Lausanne, Switzerland in 2014 again as post-doctoral research associate. His research interests are Continuum Mechanics, Nonlinear Elasticity, and Electromagnetic coupling in solids. He has published 7 journal papers in these areas.

Monday, Jan 12, 2015, Time: 5:15 PM, Venue: ME Conference Room


Dr. Arghya Das, Assistant Professor, Department of Civil Engineering, IIT Kanpur


"Compaction bands in carbonate rocks: material instability or structural artifacts?"

Abstract:

Compaction bands are narrow localized deformation zones usually observed in porous granular rocks. Under field and laboratory conditions these structures are found to be oriented orthogonally to the maximum compressive principle stress, while the microscopic observation of their internal structure has revealed the presence of densely packed fragmented rock grains. Theoretically the formation of compaction bands is predicted using the discontinuous bifurcation theory at constitutive level, considering strain rate discontinuity across the band. These predictions are often validated against experimental observations, which are mostly derived from triaxial compression tests. Some experimental studies, however, show that horizontal compaction band can form even under one-dimensional deformation conditions, such as those imposed by oedometric testing and K0consolidation. However, localization analyses of one-dimensiona l compression processes performed at the constitutive level suggest that pure compaction bands are not the preferential mode of strain-localization along these paths. In the present study, the heterogeneous compaction of carbonate rock samples is addressed via boundary value analyses, showing that both material constitutive laws and kinematic constraints imposed at the structural level represent an important control for the genesis and propagation of these important geological features of the Earth's crust.


About the speaker:

Dr. Arghya Das joined IIT Kanpur in July 2014 as an Assistant Professor in the Department of Civil Engineering. He obtained his doctoral degree from The University of Sydney, Australia, Department of Civil Engineering in 2013. He earned his Bachelor degree in Civil Engineering from Jadavpur University, Kolkata in 2006 and Masters in technology from IIT Bombay in 2009. Prior to joining IIT Kanpur he worked at Northwestern University, USA as a Post-Doctoral Researcher. His research interests include constitutive modelling and instability analysis of granular and cementer granular materials related to geotechnical engineering.

Monday, January 05, Time: 5:15 PM, Venue: ME Conference Room


Dr. Indranil Saha Dalal, Assistant Professor, Department of Chemical Engineering, IIT Kanpur


"Dynamics of isolated polymer chains in planar flows"

Abstract:

In this study, we investigate various aspects of the conformational and dynamic behavior of isolated polymer chains in planar flows using Brownian Dynamics (BD) simulations with chain models encompassing multiple resolutions. Using pre-averaged equations for the normal modes coupled with an appropriate representative spring constant, we develop a model to capture the dynamics of the chain observed in the BD simulations. We show that, for planar flows with varying amounts of extensional and rotational components, the transient growth of chain stretch and stress, in addition to the values at steady state, is predicted quite accurately by our model. Thus, in principle, this model should provide an improvement over the FENE-P, which was formulated by Bird and co-workers decades ago and is known to provide poor predictions for chain dynamics in shear flows. Next, we also present a detailed analysis of the chain deformation at steady state in shear flow, as the flow rates range from weak to ultra-high. Our simulations reveal that, in the absence of any excluded volume, the chain compression obtained at high shear rates in several earlier studies is an artifact of insufficient chain discretization. We show that the chain tumbling at strong shear rates occurs by the formation of loops whose length is limited by the time required to stretch them, and derive scaling laws from a balance of convection and diffusion of monomers in those loops. Our analysis and results presented here corrects the previously reported scaling laws obtained by using coarse-grained bead-spring models, which fails to capture the correct physics at strong shear rates that can excite a single spring away from equilibrium.


About the speaker:

Dr. Indranil Saha Dalal obtained his Undergraduate degree in Chemical Engineering from Jadavpur University, Kolkata (2003) followed by Masters in Engineering (2005) degree from the Indian Institute of Science in Bangalore. He worked for a couple of years (2005-2007) as an Engineer in the Water and Process Technologies division of General Electric (GE) at Bangalore. He joined the Doctoral program at the University of Michigan (USA) in 2007 and earned a PhD in Chemical Engineering with a Masters in Mathematics in 2013. He has been an Assistant Professor in the Department of Chemical Engineering at IIT Kanpur from July 2014.

Friday, Jan 02, 2015 Time: 5:15 PM, Venue: ME Conference Room


Dr. Rakesh Ranjan, Los Alamos National Laboratory, Nuclear Engineering and Non-Proliferation Div, Los Alamos, NM 87544


"Higher Order Spectral/hp Solutions of CFD and Free Surface Flow Problems"

Abstract:

Least squares finite element method (LSFEM) has been proposed as a new computational technique for solving computational fluid dynamics (CFD) problems. For this formulation one does not need to satisfy the LBB condition. In the context of LSFEM the standard implementation has been usage of Jacobi preconditioning for solving the least squares system. We extend the procedures used to obtain LSFEM solutions to more elegant pre-conditioners for the solutions of linear systems namely Multigrid methods. The Multigrid preconditioned conjugate gradient method is employed to solve the driven cavity and Backward facing step problems. Parallelism of the algorithm is explored and we obtain super-linear to linear speedup. While solving CFD problems with mixed finite element method one encounters stability issues and ensuring the convergence of the Navier-Stokes equations is often an issue with iterative solvers. We utilize lower order SUPS stabilized finite element methods for solving incompressible flow problems. This formulation also does not need to adhere to the LBB condition and admits equal order interpolations for the velocity and pressure variables. SUPS stabilized finite element methodology is extended to the spectral/hp framework for solving CFD problems. The new formulation is validated with analytical solutions available for Kovasznay flow and extended to solve an array of benchmark two and three dimensional CFD problems. A new methodology in literature that has been proposed is the Fictitious Domain method (FDM) for solving flow past different objects without the usage of body fitted meshes to faithfully represent the flow field around complex geometries on a fixed Cartesian product grid. FDM methods have been applied to CFD problems with the finite volume and Galerkin finite element approximations so far. We extend the FDM methodology to stabilized formulations and set out to obtain flow fields around a circular cylinder for an Re of 20 and 40. Different case studies for flow past an ellipse at Re-100 are demonstrated. The effect of axis ratio on the onset of Von-Karman vortex street is examined. An array of two elliptical shaped cylinders facing the flow-field is examined and anti-phase mode of vortex shedding is verified as observed in experimental literature. Volume of fluid (VOF) and level set methods (LSET) have been utilized for solving free surface flow problems. We utilize the level set methodology (in a spectral framework) to solve the classical problems of dam break and sloshing of two fluids of different densities in a tank. Stabilized finite element methodology is used in conjugation with the LSET equation to model the free surface evolution in transient. With the volume of fluid method we utilize an L1-L2 projection algorithm to solve an array of free surface flow problems with surface tension effects.


About the speaker:

Dr. Ranjan is currently working as a Research Associate with the Nuclear Engineering and Non-Proliferation Division at Los Alamos National Laboratory. He obtained his Doctorate from Texas A & M University from the Department of Mechanical Engineering. Subsequently, he worked as a Post Doctoral Research Fellow with the University of Texas, San Antonio, Department of Mechanical Engineering. Prior to that he was working as a Staff Engineer for an Engineering firm in Pennsylvania. He holds Masters and undergraduate degrees from Pennsylvania State University, University Park and the Indian Institute of Technology, Kharagpur. His research area has been involved with higher order spectral methods for solving computational fluid dynamics (with least squares finite element and stabilized finite element methods) and structures problems (beams, plates, and large deformation analysis). In CFD he has ventured into solving incompressible Navier-Stokes and free surface flow problems (with both Level Set and Volume of Fluid methods).

Seminars : Fall Semester 2014-15

Friday, Dec 05, 2014, Time: 5:15 PM, Venue: ME Conference Room


Dr. Pritam Chakraborty, Computational Materials Scientist, Idaho National Laboratory, USA


"A Wavelet based Multi-time Scale Method to Investigate Microstructure Sensitive Fatigue Crack Nucleation in Ti-alloys"

Abstract:

The fatigue life and number of cycles to crack nucleation in Ti-alloys exhibit considerable variation. The underlying microstructure has been observed to have significant influence on the scatter and needs consideration for accurate life prediction of these alloys. Such microstructure dependent modeling can provide safe operational limits, optimal design safety factors and prevent premature retirement of components from service. The strong elasto-plastic anisotropy of Ti-alloys cause significant load shedding induced stress concentration near grain boundaries and is perceived to be the primary driver of microstructure-dependent crack nucleation. Though crystal plasticity based finite element method (CPFEM) is fairly successful in capturing these localized stress concentrations, it requires very small time steps for stable numerical integration. Hence, CPFEM based fatigue simulations for large number of cycles till crack nucleation become computationally prohibitive. To alleviate this issue, a wavelet based multi-time scale method was developed, motivated from the dual-time scale evolution of CPFE variables under cyclic loading. A transformation of the CPFE variables to the wavelet space then enabled decoupling and integration in the coarse time-scale with much larger time steps. With the use of this multi-time scale algorithm, huge computational savings were obtained with fairly accurate solutions. A non-local crack nucleation criterion based on the Stroh model was then utilized to predict the cycles to crack initiation. Subsequently, correlations between the microstructural descriptors, load forms and cycles to crack nucleation were developed to provide engineering scale predictions of fatigue life.

Friday, Nov 21, 2014, Time: 5:15 PM, Venue: ME Conference Room


Dr Geoff Dearden, Reader in Laser Engineering, Academic Leader, Laser Group & LEC, School of Engineering, University of Liverpool United Kingdom


"Engineering and manufacturing the future with laser light"

Abstract:

The University of Liverpool is internationally recognized for its research, knowledge and innovation. Its pioneering reputation attracts students, experts and partners from around the world. Through its research, teaching and collaborations it seeks to be life changing and world shaping. The University is rated in the world's top 1% of universities and is a member of the UK's Russell Group of research-led institutions, globally recognized for its work in health and life sciences, science and engineering, and humanities and social sciences. The Centre for Materials and Structures in the School of Engineering is home to one of the world's longest established and internationally recognized laser materials processing research groups. The Laser Group's pioneering research, teaching and knowledge exchange has evolved from early roots of laser cutting, welding and cladding of metals to today's pioneering work on ultra short pulse laser optical techniques formicro/nano scale processes, laser ignition for car engines and laser forming. The talk will briefly introduce the University of Liverpool and research areas within its School of Engineering, before presenting an overview and recent highlights of research in laser engineering and advanced manufacture. Current opportunities for new research links with the University of Liverpool will also be outlined.

Monday, Nov 17, 2014, Time: 5:15 PM, Venue: ME Conference Room


Dr. Siladitya Pal, Post Doctoral Research Associate, Computational Biomechanics Lab, Department of Bioengineering, University of Pittsburgh, Pennsylvania, USA.


"Modeling Failure of Complex Material Systems: Next-gen Energy Storage Materials"

Abstract:

Lithium-ion batteries (LIB's) are currently at the forefront of electrochemical energy storage technologies. Commercial LIB's use graphite as anode and lithium metal oxide as cathode. Silicon anode offers ~10 times higher capacity than graphite. Thus Si has a great promise to be the next generation electrode. However, electrode mechanical degradation leading to capacity loss is a major concern. Amorphous silicon thin film deposited on copper current collector is a promising candidate for the high capacity lithium-ion battery (LIB) anode. However these systems exhibit a rapid capacity fade, and as a result, poor cyclic performance. Interfacial delamination due to lithium intercalation induced stress is the primary reason behind this capacity fade. For the case of a clean interface, crack blunting resulting from the plastic flow of the metallic substrate will eventually arrest the delamination. However, experimental observations suggest a complete delamination of the thin film from the substrate indicating the existence of interface embrittling mechanisms. Further experiments have revealed the evidence of segregation of lithium into the interfacial region that can potentially embrittle the interface. The focus of the current study is to investigate the role of such irreversible mechanisms at the interface on its delamination response during electrochemical cycling.

Friday, Nov 14, 2014, Time: 5:15 PM, Venue: ME Conference Room


Dr. Bidyut Pal, Research Associate, Department of Mechanical Engineering, Imperial College London, UK


"Advances in Biomechanical Analysis of Orthopaedic Implants: Numerical and Experimental Investigations"

Abstract:

This talk will focus on my doctoral and post-doctoral research activities. My doctoral research dealt with analysing surface replacement of the hip joint, particularly the femoral side. Failure mechanisms of the femoral resurfacing implant include femoral neck fracture in the short-term and mechanical loosening in the long-term. The precise relationship between the cause and the effect and the extent to which biomechanical factors may play a role in this process, were not clearly understood. Results of investigations on load transfer, using finite element analysis and experimental technique, within the natural and implanted femur will be presented addressing the risk of femoral neck fracture. The effect of bone remodelling and its relationship with the eventual risk of implant loosening will also be explained. Subsequently, alternative measures for improved designs will be proposed. My post-doctoral research is about the design and development of novel implants for osteoporotic femur and revision knee surgery. Osteoporotic patients have much higher risk of hip fracture than the healthy group. Hip replacement is considered to be the preferred treatment option for fractured femurs. However, currently available designs are not suit able for osteoporotic femur. Background of the proposed design suitable for osteoporotic patients will be discussed. The number of revision total knee replacement is growing. Severe bone-loss is encountered frequently in revision knee surgery. Traditionally, stem extensions of variable lengths are used to achieve stability and alignment of the revised joint. However a long stem is more bone-destructive and increases the risk of stress-shielding and subsequent implant loosening. An overview of the proposed alternative revision knee implant system will be presented.

Monday, Nov 10, 2014, Time: 5:15 PM, Venue: ME Conference Room


Mr. Vinamra Agrawal, Doctoral Student, Department of Mechanical Engineering CalTech, USA


"Shock wave propagation in composites and active materials"

Abstract:

Under the application of high strain rate loading, like impact of a projectile on a target, shock waves travel through a material. These waves are characterized as a discontinuity propagating through the system across which material properties jump. They can cause materials to reach very high stress states and if transmitted without mitigation, can lead to failure of key components. It is hence important to understand how shock waves propagate in heterogeneous materials. Shock waves are also being used to obtain pulsed currents and voltages of very high magnitude from active materials like ferroelectrics and ferromagnets. So it is important to characterize the large deformation dynamic behavior of active materials. In this talk, I will discuss my work on shock wave propagation in composites and active materials. We start with a plate impact problem on a layered (not necessarily periodic) target. We obtain analytic solution to the entire wave propagation problem and study the influence of different parameters and arrangement of layers on the shock propagation. Next we study a front propagation problem in a stationary ergodic medium. Using the concepts of viscosity solutions and stochastic homogenization, we obtain local probabilistic bounds on the front roughness. Finally we look at the impact problem on a ferroelectric material. We develop a continuum theory of the dynamic large deformation behavior of a ferroelectric material. We derive the driving force and the governing equations of the process.

Monday, Nov 03, 2014, Time: 5:15 PM, Venue: ME Conference Room


Dr. Imran A. Khan, Reactor Safety Division, Bhabha Atomic Research Centre, Mumbai


"Shock wave propagation in composites and active materials"

Abstract:

Structural integrity of pressure-retaining components is important for safe operation of power plants. In-service inspections of many nuclear power plants have revealed that in comparison to base material, weld joint locations are more critical. At present, fracture mechanics based approaches are widely used to analyse the integrity of pressure-retaining components with postulated flaws. The flaws are postulated at critical locations (highest service loads coincident with poorest material properties) in order to meet the regulatory requirements. The existing flaw assessment procedures were essentially developed for macroscopically/nominally homogeneous materials. Since the weld joints exhibit distinct microstructural phases, they lead to significant mismatch in mechanical properties with respect to base material. The focus of present talk is on Plasticity and Fracture aspects of strength mismatched welds. Recent developments in the field of limit analysis, experimental evaluation of fracture toughness, and characterization of crack tip stresses in strength mismatched welds will be presented.

Monday, Oct 27, 2014, Time : 5:15 PM, Venue: ME Conference Room


Dr. Indrajit Chakraborty, Department of Thermal Engineering and Fluid Mechanics, Fluid Mechanics Research Group, Carlos III University of Madrid, Spain


"The dynamics of gas bubbles in an acoustic field"

Abstract:

Gas-liquid systems are part of many natural processes and they are widely used in industry. Among the natural processes, the tiny air bubble entrainment in liquid after the impact of a raindrop on the surface of a liquid and the bubbles creation after breaking waves on the ocean become prominent. As such situations, the generated bubbles pulsate at their natural frequency and emit sound. The dynamics of gas bubbles are of great interest for wide range of practical applications in metallurgical industry, sonochemistry, ultrasonic cleaning and biomedical sciences. Recently in biomedical applications such as in medical diagnostics and therapeutics, ultrasound contrast agents (UCAs) composed of gas-filled encapsulated microbubbles play an important role, which motivates our present study. In ultrasound medical therapy, the microbubbles as drug-carriers are used to transport drug inside the blood stream and to release drug to the specific locations. UCAs in medical diagnostics are employed to enhance the medical image of the structures or fluids within the body. In all those natural processes and practical applications, the common feature is the observation of the volume oscillation of the bubbles driven by an external acoustic wave. In view of experimental and theoretical limitations, a numerical methodology for simulating the dynamics of gas bubbles in response to an acoustic pressure, which ranges from low to moderately high pressure amplitudes, in an unbounded quiescent liquid is presented. To study this problem, the axisymmetric Navier-Stokes equations with a coupled level set and volume of fluid (CLSVOF) method are solved by means of a finite difference formulation on a fixed grid. In this method, the liquid phase is assumed incompressible while the gas phase is treated as compressible. The gas bubble is considered to behave isentropically with low Mach number flows. First, the method has been implemented to study the volume oscillation of a spherical bubble and the computed results are compared with the numerical solutions of Rayleigh-Plesset equation. As an illustration of the performance of the present approach, the dynamics of the interaction between two oscillating co-axial bubbles in the presence of imposed acoustic pressure in an ambient liquid are then presented. The two bubbles undergo volume, shape and time periodic translational oscillations, and simultaneously approach each other with time due to the secondary Bjerknes force.

Monday, Oct 20, 2014, Time:5:15 PM Venue: ME Conference Room


Dr. Sagar Chakraborty, Assistant Professor, Department of Physics, IIT Kanpur


"Noise induced Hopf bifurcation: stabilizing oscillations or ... ?"

Abstract:

On applying noise near the bifurcation point of a subcritical Hopf bifurcation, the unstable limit cycle seems to be stabilized. In this elementary talk, we shall discuss the phenomenon and the explanation for it.

Monday, Oct 13, 2014, Time: 5:15 PM, Venue: ME Conference Room


Prof. K. Srihari, Department of Chemistry, IIT Kanpur


"Three men, a junction, and the rate of a reaction"

Abstract:

How does one understand the mechanism of a reaction? This question, dating back to more than a century and predating quantum mechanics, continues to pose challenges even today. Several rate theories have been proposed and each one assumes something about the nature of the underlying intramolecular dynamics. A real "fly in the ointment" has been the phenomenon of intramolecular energy flow which seems to confound theorists and experimentalists alike. So much so that a famous theorist once remarked that a useful definition of intramolecular vibrational energy flow is something that experimentalists do not understand or cannot assign! Why is understanding the energy flow dynamics so difficult? In this talk I will try and answer this question. At the same time, I will argue that there are beautiful connections between studies of celestial mechanics and molecular reaction dynamics. These connections, which exploit the recent developments in Hamiltonian dynamics, are starting to yield insights that just might let us devise intelligent methods to control the intramolecular dynamics.

Wednesday, Sept 24, 2014, Time: 5:15 PM, Venue: FB-364


Dr. Shorya Awtar, Associate Professor, Department of Mechanical Engineering , University of Michigan, Ann Arbor


"Cost-Effective Instrument Technology for Advanced Laparoscopy"

Abstract:

I will present the design, development, and commercialization of the FlexDex Surgical Technology. FlexDex provides enhanced dexterity, intuitive control, and natural force feedback via a purely mechanical and ergonomic instrument designed for Minimally Invasive Surgery (MIS). These features enable complex MIS procedures such as suturing, knot-tying, and fine dissection that require wrist-like articulation at the instrument tip. The patented innovations in FlexDex allow surgeons to perform these complex MIS procedures with minimal training and at an affordable cost. This is expected to increase the adoption of MIS, resulting in faster recovery for patients and revenue benefits for hospitals. FlexDex provides a platform technology that can be adapted for various instrument tips including needle driver, dissector, grasper, scissors, and electro-cautery. This versatility can potentially impact operations in several surgical specialties including gynecology, urology, general, thoracic, colorectal, and pediatric.

Monday, Sept 22, 2014, Time: 5:15 PM, Venue: ME Conference Room


Dr. Dibakar Sen, Center for Product Design and Manufacturing, and Department of Mechanical Engineering, Indian Institute of Science Bangalore


"Genesis of an Efficient Algorithm for Mechanical Assembly Sequencing"

Abstract:

How to put the components and sub-assemblies to construct an assembled product constitutes the problem of assembly sequencing. It concerns spatio-temporal, physics, manufacturing tolerances, flexibility, tool, tooling and human-factor issues. Although temporal ordering of the motion of components is the central challenge, many simplistic assumptions on the motion of the components are generally imposed to make the problem computationally tractable. The talk will focus on the synergistic convergence of a few algorithms developed by us in diverse contexts for effectively solving the problem of assembly sequencing using rectilinear and orientation-preserving motions of the components. I shall discuss concepts of slice representation for multi-solid discretization which was originally developed for the fast and robust computation of volume fractions, unit-cube representation for directions which was originally developed for vision modeling of digital human models and later found suitable for representing generic ranges of motion of 3DOF spherical joints as well, and polyhedral-convex-cone representation for collision prediction of convex objects which are fundamentally open solid cones and hence conventional notion of B-rep Boolean cannot be applied on them! What they together enable us is to transform these open cones as polygons on the unit-cube and then perform exact Boolean operations on millions of polygons on it in a fast, robust and stable manner without ever performing an explicit boundary evaluation. For the assembly sequencing problem, the set of components are presumed to be given as tessellated B-reps in the desirable assembled configuration. We compute the pair-wise collision potential and represent them using slice representation on a unit-cube. This step is rather computation intensive; hence, though it is very fast in the context of the state of the art, it cannot be done in real time. Hence we do this offline and save the results. However, the pair-wise unit-cubes can be composed to construct or validate multiple assembly sequences in real-time. The precision of the algorithm is demonstrated using scenarios involving a solid-angle of assembly directions, a sheet of directions and those involving only singular directions.

Monday, Sept, 15, 2014, Time: 5:15 PM, Venue: ME Conference Room


Dr. K. Hariharan, Post Doctoral Research Fellow, Pohang University of Science and Technology (POSTECH), South Korea


"Modification of fatigue strain-life equation to account in-plane anisotropy in sheet metals"

Abstract:

The thermo-mechanical processing history induces anisotropy of mechanical properties in the cold rolled sheet metals. This texture induced anisotropy influences forming, assembly and fatigue behaviour of sheet metal components. Using phenomenological models of plasticity, the effect of anisotropy is accounted for in the constant amplitude cyclic behaviour of metals. The well-established Coffin-Manson relation for strain-fatigue life relation is modified by introducing the influence of in-plane anisotropy in the fatigue constants. The importance and application of the anisotropic fatigue model will be discussed. Keywords: plastic anisotropy, yield criterion, strain-life, Coffin-Manson relation, Anisotropic hardening.

Monday, Sept 08, 2014, Time: 5:15 PM, Venue: ME Conference Room


Dr. Sathesh Mariappan, Department of Aerospace Engineering, Indian Institute of Technology Kanpur


"Investigation of dynamic stall and transition in helicopter rotor blades"

Abstract:

Dynamic stall on rotor blades severely restricts the flight envelope of helicopters. Dynamic stall is defined as an entire series of events occurring in the flow field, by which the lift is increased beyond the static stall limit in a pitching airfoil. Dynamic mode decomposition (DMD) is applied to investigate the unsteady flow field around an airfoil pitching at a constant frequency. Every DMD mode is associated with a frequency equal to the pitching frequency or its higher harmonics. This enables to identify the spatial dominance of a particular frequency and thereby locate the source of high frequency oscillations. It is proposed that this decomposition is more suited than the existing proper orthogonal decomposition. On the other hand, the laminar to turbulent transition location dictates the performance of the rotor blades. This transition location is identified by temperature sensitive paint, along with the rotating mirror technique to achieve large exposure time for the camera.

Sept 03, 2014, Time: 5:15 PM, Venue: ME Conference Room


Dr. Sarvanan Balysamy, Research Associate, University of Cambridge, United Kingdom


"Combustion studies using optical diagnostics"

Abstract:

In direct injection gasoline engines, stratified mode of combustion increases the fuel efficiency and lowers CO2 emissions. We need a complete understanding of the fundamentals of stratified flame propagation in order to take advantage of the benefits of stratified combustion. An experimental investigation of laminar flame propagation through stratified mixture fields was carried out in order to determine the memory effect of stratification on the enhancement of flame propagation. To realize that, an original PIV algorithm was developed to directly measure the local laminar burning velocity that I will present in the talk. The second part of the talk is an experimental study on thermoacoustic instabilities, which remains one of the biggest problems facing manufacturers of gas turbines. In these devices, the acoustics is usually linear, but the flame's heat-release response to incident perturbations is highly nonlinear. The overall thermoacoustic system is therefore expected to behave as a coupled nonlinear dynamical system. A dynamical systems approach has been used to study the nonlinear interaction between self-excited oscillations and forced oscillations in a combustor containing a swirl-stabilized turbulent premixed flame. Coal thermal power plants provide almost 28% of world's primary energy consumption and emit around 36% of all CO2 pollutants. Oxyfuel coal combustion technology is a possible way to address the pollution problem. My third part of the talk is the implementation of optical diagnostics to a laboratory-scale oxyfuel pulverized coal combustor. The aim of the project is to study the flame structures under various O2/CO2 conditions and to generate database for the support of numerical simulations. I will present some of our findings and the challenges involved in applying the optical diagnostic techniques to the coal combustion.

18 Aug, 2014 Monday, Time: 5:30 PM, Venue: ME Conference Room


Dr. Mangal Kothari, Department of Aerospace Engineering IIT Kanpur


"Control and Guidance of Aerospace Systems"

Abstract:

The talk will discuss guidance and control schemes for autonomous missions. In the first part, a probabilistically robust motion planner for unmanned aerial vehicles (UAVs) will be discussed that combines philosophies of probabilistic approaches that include rapidly-exploring random tree (RRT), chance constraint, and overlapping coefficient. The motion planner takes various forms of uncertainties present in the real world into account while planning the paths. In the second part, the focus will be on coordination of multi-UAV systems. Under coordination problems, I will present cooperative algorithms for formation control, target capturing, and geo-localization. I will also present an optimal control/guidance scheme to solve two point boundary value problems (TPBVPs) efficiently. The algorithm was used to design a robust guidance strategy to address burnout uncertainty in solid motors for long range flight vehicles. Finally, I will discuss a neuro-adaptive approach for control design.

Monday, Aug 11, 2014, Time: 5:15 PM, Venue: ME Conference Room


Dr. Sameer Khandekar, Department of Mechanical Engineering IIT Kanpur


"Thermal-fluidic Transport in Talyor Slugs and Bubbles"

Abstract:

Transport mechanisms of heat, momentum and species under two-phase flow conditions in mini/micro systems are greatly affected by local distribution of the phases or flow patterns in the channel. Taylor slug/bubble flow, a sub-set of slug flows occurring in mini/micro-systems, is typically characterized by a sequence of long bubbles which are trapped in between liquid slugs. This unique intermittent flow pattern requires understanding of transport phenomena on global, as well as on local scales. Over the past years, we have conducted several experiments, incorporating high speed video graphy, Infra-red thermo graphy and PIV, with supporting flow simulations, to discern the subtle mechanisms of heat and momentum transport in (i) Isolated Taylor liquid slugs (ii) Gas-Liquid Taylor bubble flows (ii) Vapor-liquid Taylor slug-bubble systems. Both, steady-state as well as oscillating Taylor flows, have been scruitinized. Many novel and upcoming microfluidic applications involve these unique flow situations. This talk will highlight the main findings and provide an outlook on the unresolved issues.

Monday, Aug 04, 2014, Time: 5:15 PM, Venue: ME Conference Room


Dr. N. Kumbhakarna, Pennsylvania State University USA


"Combustion analysis of RDX propellants and novel high-nitrogen propellant ingredients"

Abstract:

Propellants are materials having high energy content which can undergo combustion and sustain it in the absence of an ambient oxidizer. Propellants are used in space propulsion systems, guns, automobile air bags and ejection seats of airplanes where generation of high pressure within a very short time is necessary. To make sure that the above mentioned devices are well designed, it is essential to select an appropriate propellant for the particular application under consideration. In addition, it is also essential that the burning characteristics of the selected propellant are understood properly. For example, if a solid propellant is used in a rocket booster, thorough information must be available of its burn rate and specific impulse for the specified operating conditions. The combustion phenomena of a propellant are complex and involve different processes including, among others, decomposition, oxidation, phase conversion, species diffusion, etc. Most of the propellants used in practical applications contain two or more ingredients. Research presented in this seminar is directed towards enhancing the knowledge of combustion behavior of the widely used RDX propellant and that of the high-nitrogen compounds which can be potentially used as propellant additives. These compounds are triaminoguanidinium azotetrazolate (TAGzT) and guanidinium5-aminotetrazole (GA). In first part of this research a detailed model of steady-state combustion of a pseudo-propellant containing cyclotrimethylene trinitramine (RDX) and triaminoguanidinium azotetrazolate (TAGzT) is presented. To improve the predictive capability of such models, it is essential to understand the liquid-phase decomposition chemistry of propellants and their additives. Hence in the second part, the decomposition of liquid-phase RDX was studied using FTIR spectroscopy. Finally in the third part, a detailed reaction mechanism of the decomposition of the high-nitrogen compound guanidinium 5-amino tetrazolate (GA) in the liquid phase is formulated. This compound is chosen because it has a simpler molecular structure as compared to TAGzT.

Friday, July 25, 2014, Time: 5:15 PM, Venue: ME Conference Room


Prof. Girijesh Prasad, Faculty of Computing & Engineering, University of Ulster, N. Ireland, UK


"Advancing Brain-Computer Interface Towards Practical Applications"

Abstract:

A brain-Computer interface (BCI), also known as brain-machine interface (BMI), utilizes neuro-physiological correlates of voluntary cognitive tasks to facilitate direct communication between human brain and computing devices without the involvement of neuro-muscular pathways. This emerging research area has the potential to contribute significantly to enhancing the accessibility of ICT systems for the elderly and disabled people. The BCI research is, in general, progressing in two main areas: alternative communication by replacing neuro-muscular pathways and neuro-rehabilitation by helping to activate desired cortical areas for targeted brain plasticity. Current BCI systems however, lack sufficient robustness and the performance variability among users is quite high. One of the critical limitations is because of the non-stationary characteristics of the brain's neurophysiological responses, which makes it very hard to extract time-invariant stable features unique to voluntary cognitive tasks. Under these inherent limitations, devising real-world BCI applications for constant use is a real challenge. In this seminar, the presentation will focus on our recent R&D works towards robust BCI design and practical real-world applications made possible through advances in one or more BCI design phase.