Abstract:

Translating novel nanoscale manufacturing concepts from research to commercially viable technologies has proven to be very challenging. This is due to the complexity of these systems and the lack of system-level models that are essential for efficient design and control of reliable manufacturing processes. Such nanomanufacturing development efforts typically involve prolonged iterative experimental investigations prior to successful deployment, see, for example, ref. [1]. This presentation will discuss ongoing research related to several nanomanufacturing systems being investigated at the NASCENT Center. In each case, the presentation will discuss precision sub-systems that enable the process technology, in-situ sensing, and control approaches used to achieve reliable process behavior.

Common challenges across these nanomanufacturing systems include: (i) lack of reliable and validated system-level models; (ii) multi-scale physics and chemistry coupled with parameter uncertainty; and (iii) incomplete in-situ sensing that creates gaps in system understanding. This talk will discuss the use of in-situ metrology and evolutionary computational algorithms to estimate system models and to create optimal control techniques that enable reliable manufacturing processes. Exemplar manufacturing systems that will be discussed include: (i) advanced process control in nanoimprint lithography steppers to achieve sub-3nm overlay; (ii) precision sub-systems and metrology in the development of continuous roll-to-roll nanoimprint lithography; (iii) an order of magnitude enhancement in volume resolution (down to about 300 femtoliters) in high-speed multi-nozzle piezo inkjet systems; and (iv) precision sub-systems and metrology in the development sub-100nm deep silicon electrochemical etching.

S.V. Sreenivasan, “Nanoimprint lithography steppers for volume fabrication of leading-edge semiconductor integrated circuits,” Microsystems & Nanoengineering, Nature Publishing Group, Vol. 3, Article number: 17075 (2017).

Bio-sketch:

Prof. S.V. Sreenivasan’s research focuses on creating scalable nanofabrication technologies that enable novel devices in electronics, displays, and healthcare sectors. He currently serves as the director of the NSF funded NASCENT Engineering Research Center. He has received several awards for his work including the Technology Pioneer Award from the World Economic Forum, the ASME Leonardo da Vinci Award, the ASME William T. Ennor Award, and the ASME Machine Design Award. He was named a fellow of the National Academy of Inventors in 2017. Dr. Sreenivasan founded Molecular Imprints Inc. (MII), a nanopatterning spin-out from UT-Austin that has resulted in commercial products in the semiconductor and display industries. He currently serves as the Chief Technologist of Canon Nanotechnologies, Inc., a company formed as a result of the acquisition of the semiconductor business of MII by Canon Corporation in 2014. The display division of MII was acquired in 2015 by Magic Leap, Inc., a leading augmented/mixed reality company.

All interested are welcome to join via the zoom link.

Abstract:

Manufacturing of metal components is essential to every major industry, and involves complex supply chains, consumes significant natural resources, and in some cases still uses ancient techniques. Conversely, additive manufacturing (AM) promises to, ultimately, digitize the formation of objects, consolidate supply chains, and redistribute value across the product life cycle. I will provide an overview of AM techniques for metals and will highlight recent work from my research group at MIT as well as from the startup company Desktop Metal, including discrete element simulation and X-ray metrology of powder spreading; a new concept for drop-on-demand metal printing; and an extrusion-based process that enables metal 3D printing in ambient followed by high-temperature sintering. These efforts emphasize expertise in materials, computation, and automation, which are collectively critical to enabling metal AM at scale. Yet, from industry, we have learned that in some cases the greatest barriers to wider adoption of AM are limited knowledge of its technical foundations and the difficulty of quantifying its value proposition. Motivated by this, I will also share experiences from the development of professionally oriented courses focused on AM, and the launch of a consortium aiming to strengthen ties between MIT and industry in additive and digital manufacturing.

Bio-sketch:

John Hart is Professor of Mechanical Engineering, Director of the Laboratory for Manufacturing and Productivity, and Director of the Center for Additive and Digital Advanced Production Technologies at MIT. John’s research group at MIT, the Mechanosynthesis Group, aims to accelerate the science and technology of production via advancements in additive manufacturing, nanostructured materials, and precision machine design. In 2017 and 2018, respectively, he received the MIT Ruth and Joel Spira Award for Distinguished Teaching in Mechanical Engineering and the MIT Keenan Award for Innovation in Undergraduate Education. John has co-authored >175 journal publications, is a co-inventor on >50 pending or issued patents and is a co-founder of startup companies Desktop Metal and VulcanForms, and a Board Member of Carpenter Technology Corporation.

All interested are welcome to join via the zoom link.

Abstract:

Neural disorders and old age limit the ability of humans to perform activities of daily living. Robotics can be used to probe the human neuromuscular system and create new pathways to characterize, relearn, or restore functional movements. Dr. Agrawal’s group at Columbia University Robotics and Rehabilitation (ROAR) Laboratory has designed innovative technologies and robots for this purpose. These technologies have been tested on subjects in a variety of studies to understand human cognitive and neuro-muscular response. Human experiments have targeted patients with stroke, cerebral palsy, Parkinson’s disease, ALS, Vestibular disorders, elderly subjects, and others. The talk will provide an overview of some of these technologies and scientific studies performed with them.

The most common, which is also the simplest, method used for obstacle identification is Arrival Time Imaging (ATI), also called Kirchhoff Migration. It is claimed that about 80% of SEG identification problems are solved using ATI. At the other end of the spectrum, there is Full Waveform Inversion (FWI), usually with the aid of an efficient adjoint-type scheme. Computational methods based on Time-Reversal (TR) are also effective for such problems.

In this talk, we present various methods to solve time-dependent wave-based obstacle identification problems in acoustics, SEG, and structural damage evaluation. In addition, we compare the performance of various methods.

Bio-sketch:

Sunil K. Agrawal received a Ph.D. degree in Mechanical Engineering from Stanford University in 1990. He is currently a Professor and Director of Robotics and Rehabilitation (ROAR) Laboratory at Columbia University, located both in engineering and medical campuses of Columbia University. Dr. Agrawal has published more than 500 journal and conference papers, three books, and 15 U.S. patents. He is a Fellow of the ASME and AIMBE. His honors include an NSF Presidential Faculty Fellowship from the White House in 1994, a Bessel Prize from Germany in 2003, and a Humboldt US Senior Scientist Award in 2007. He is a recipient of the 2016 Machine Design Award from ASME for “seminal contributions to the design of robotic exoskeletons for gait training of stroke patients” and the 2016 Mechanisms and Robotics Award from the ASME for “cumulative contributions and being an international leading figure in mechanical design and robotics”. He is a recipient of several Best Paper awards in ASME and IEEE sponsored robotics conferences. He has also held international visiting positions that include the Technical University of Stuttgart, Hanyang University in Korea, the University of Ulster in Northern Ireland, the Biorobotics Institute of SSSA in Pisa, Peking University in China. He has successfully directed 30 Ph.D. student theses and currently supervises the research of 10 Ph.D. students at the ROAR laboratory. He is the founding Editor-in-Chief of the journal “Wearable Technologies” from Cambridge University Press. He is the Conference Chair for IEEE BioRob2020 to be hosted in New York City.

All interested are welcome to join via the zoom link.

Abstract:

Obstacle identification problems are an important class of inverse problems, where the goal is to find the location, size, and shape of a local "object" (which can be a cavity, a region made of a material different from the background material, a geometric irregularity in the boundary, etc.) in an otherwise given medium, based on some measurements of the relevant field. A sub-class of problems in this category is based on time-dependent waves. Here, a given time-dependent wave source is introduced in the medium, and the response to this source is measured at certain points in space and time. Based on these measurements, some computational method is used to identify the obstacle. Such problems occur (and are important), for example, in biomedical engineering, Non-Destructing Testing (NDT) of structures, damage evaluation, underwater acoustics, and solid earth geophysics (SEG).

The most common, which is also the simplest, method used for obstacle identification is Arrival Time Imaging (ATI), also called Kirchhoff Migration. It is claimed that about 80% of SEG identification problems are solved using ATI. At the other end of the spectrum, there is Full Waveform Inversion (FWI), usually with the aid of an efficient adjoint-type scheme. Computational methods based on Time-Reversal (TR) are also effective for such problems.

In this talk, we present various methods to solve time-dependent wave-based obstacle identification problems in acoustics, SEG, and structural damage evaluation. In addition, we compare the performance of various methods.

Bio-sketch:

Dan Givoli is a Professor at the Department of Aerospace Engineering, Technion – Israel Institute of Technology. He holds the Lawrence and Marie Feldman Chair in Engineering at the Technion and is a fellow of the International Association for Computational Mechanics (IACM). He was the former president and one of the three founders of the Israel Association for Computational Methods in Mechanics (IACMM), which is affiliated with ECOOMAS and with IACM. Dan Givoli is the associate editor of two journals: Wave Motion and Journal of Computational Acoustics. He is also a member of the Editorial Board of seven other journals, including Int. J. Numerical Methods in Engineering (IJNME), Computer Methods in Applied Mechanics and Engineering (CMAME), Solid and Structural Mechanics Committee (ECCSM) of ECCOMAS. He served as an elected member of the IACM General Council for 16 years. Dan Givoli completed his Ph.D. degree at Stanford University in 1988. He has won several Excellent Teaching awards at the Technion, held Visiting Professor positions at four other universities: Tel Aviv U., RPI, NPS, and TU Delft. He has published over 140 papers in scientific journals, including four highly cited review papers, and many more papers in conference proceedings and edited books.

All interested are welcome to join via the zoom link.

Abstract:

Modern economies and societies are highly dependent on energy, and its use is increasing at a fast rate. Providing for these needs in a sustainable way can only be done by using renewable energy resources. However, in order to replace fossil fuels, the alternatives need to address the user needs, particularly availability and dispatchability. Concentrated Solar Power (CSP) has the potential to contribute a large share of the world’s energy requirements, taking advantage of the potentially high efficiency that can be attained in combination with storage capability. Presently, however, CSP’s contribution to the global energy mix is marginal and increasing at a very low pace. The proliferation of other, lower-cost power generation technologies is proceeding at a much larger scale, despite their inability to provide 24/7 year-round supply and dispatchability.

In a recent study, we proposed a methodology for optimizing the selection process of an energy solution for a wide range of applications to better address customer goals and needs. The method enables a rigorous comparison between alternative technologies and system configurations, and an example presented in this paper for a self-sufficient 24/7 year-round power generation, identifies a specific modular CSP configuration – possibly combined with other technologies – as a most advantageous solution.

Bio-sketch:

Prof. Jacob Karni received his BS in civil engineering and his MS and Ph.D. in mechanical engineering from the University of Minnesota (1979, 1982, 1985). He was an Assistant Professor at SUNY in Stony Brook, NY (1984-1989), and joined the faculty of the Weizmann Institute in 1989. Prof. Karni’s research focuses on energy conversion processes, primarily for solar energy and clean fuel alternatives. His work in solar energy includes the development of new methods for concentration, absorption, conversion, transmission, and storage of solar energy, and the implementation of these methods in industrial systems. His research has produced several novel solar receivers capable of working at very high temperatures with highly concentrated sunlight while supplying heat to various high-temperature applications. His research has helped make solar-thermal cycle configurations more efficient. He has also created a novel concentrated photovoltaic configuration. He has demonstrated a new method for enhanced high-temperature electrolysis for the production of syngas (synthetic gases) from carbon dioxide and water. His goal is to create solar system configurations for a 24/7, year-round supply of electricity and clean, synthetic fuel. A commercialization program based on Prof. Karni's findings is presently underway.

All interested are welcome to join via the zoom link.

Abstract:

The unceasing growth in computational power and the development of new software tools and numerical algorithms are opening up exciting areas of research, discovery & translation in mechanics and biomedical engineering. Consider the mammalian heart, which has been sculpted by millions of years of evolution into a flow pump par excellence. During the typical lifetime of a human, the heart will beat over three billion times and pump enough blood to fill over sixty Olympic-sized swimming pools. Each of these billions of cardiac cycles is itself a manifestation of a complex and elegant interplay between several distinct physical domains including electrophysiology, muscle mechanics, hemodynamics, flow-induced valves dynamics, acoustics, and biochemistry. Computational models provide the ability to explore such multi-physics problems with unprecedented fidelity and precision. In my talk, I will describe several projects that demonstrate the application of powerful computational tools to problems ranging from chemo-fluidics of clot formation to fluid-structure interaction in prosthetic heart valves. The talk will culminate with a brief discussion on a new project where we are using computational aeroacoustics to analyze wing-tone based communication in mosquitoes.

Bio-sketch:

Rajat Mittal is a Professor of Mechanical Engineering at the Johns Hopkins University (JHU) with a secondary appointment in the School of Medicine. He received the B. Tech. degree from the Indian Institute of Technology at Kanpur in 1989, and the Ph.D. degree in Applied Mechanics from The University of Illinois at Urbana-Champaign, in 1995. His research interests include fluid mechanics, computing, biomedical engineering, biofluids, and flow control. He is the recipient of the 1996 Francois Frenkiel Award from the Division of Fluid Dynamics of the American Physical Society, and the 2006 Lewis Moody Award from the American Society of Mechanical Engineers. He is a Fellow of the American Society of Mechanical Engineers and the American Physical Society, and an Associate Fellow of the American Institute of Aeronautics and Astronautics. He is an associate editor of the Journal of Computational Physics, Frontiers of Computational Physiology and Medicine, and the Journal of Experimental Biology.

All interested are welcome to join via the zoom link.

Abstract:

We study the linear stability of a vertical interface separating two fluid columns of different densities under the influence of gravity. The interface plane is parallel to the direction of gravity, corresponding to an accelerating Kelvin-Helmholtz configuration. This configuration was investigated recently at Caltech by Gat et al. (2017), who performed direct numerical simulation (DNS) of this flow. Here, we are interested in a theoretical understanding of the early phases of evolution, where a small-amplitude perturbation analysis can be carried out. In the first limit, we consider immiscible flow with surface tension and obtain a closed-form solution of the time evolution of the interface amplitude. The solution is non-modal and expressible as a function of the parabolic cylinder function. Secondly, we consider the viscous (miscible) case. Initially, we assume quasi-steady-state (QSSA) of the base flow and pose the problem as an eigenvalue problem. Subsequently, we carry out adjoint-based optimization of the most amplified eigenmode. This results in an initial condition that leads to the maximum growth of disturbances at a finite time. Results indicate that the perturbation energy of wave modes with small wavenumbers may experience substantial transient growth prior to decaying asymptotically in time. It is also found that the maximum growth rate is about one order of magnitude higher than that of the non-optimized case. The sensitivity of perturbation growth with respect to the initial time, density, and viscosity ratios will be discussed.

Bio-sketch:

Carlos Pantano received his Bachelor's degree in Industrial Engineering with a specialization in Electrical Engineering from the University of Sevilla in Spain. He received a Masters in Applied Mathematics from Ecole Centrale Paris in France and a Masters and Ph.D. in Mechanical Engineering from the University of California San Diego. He was a Senior Postdoctoral Engineering from 2000 to 2001 at the Office National d'Etudes et de Recherches Aerospatiales in France and then joined the California Institute of Technology as a senior post-doctoral associate and later as a senior research scientist until 2006. He was a faculty at the University of Illinois at Urbana-Champaign from 2006 until 2018. Currently, he holds the rank of Professor in Aerospace and Mechanical Engineering at the University of Southern California. Professor Pantano received the Presidential Early Career Awards for Scientists and Engineers (PECASE) in 2006. He is currently an Associate Fellow of the American Institute of Aeronautics and Astronautics (AIAA) and a member of the American Physical Society (APS), Society for Industrial and Applied Mathematics (SIAM), and the Combustion Institute. He serves in the editorial boards of Combustion Theory and Modelling, AIAA Journal, and is an associate editor of the Journal of Fluid Mechanics.

All interested are welcome to join via the zoom link.

Abstract:

I will introduce our research portfolio including combustion, biofuels, CCS, and fuel production. I will discuss in more detail our recent work on the development of materials, reactors, and systems for clean energy including carbon capture, hydrogen production, and CO2 reuse. Oxy-combustion is an efficient power plant technology with carbon capture. Our recent work addresses how to extend the fundamental knowledge base of air combustion to oxy-combustion, including scaling of critical phenomena. Efficient air separation is needed to support oxy-combustion, and we will show how using metal oxides/pervoskites enables the integration of air separation and combustion. As decarbonization of the energy system expands, alternative fuels/energy carriers such as hydrogen will be widely used, and “CO2 reuse” could contribute to their formulation. We have demonstrated how to use similar techniques for water splitting, CO2 reduction as well as the conversion of natural gas to chemicals.

Bio-sketch:

Ahmed F. Ghoniem is the Ronald C. Crane Professor of Mechanical Engineering. He is the principal investigator of the Center of Excellence in Energy and director of the Center for Energy and Propulsion Research at MIT. His research covers clean energy and combustion with a focus on CO2 capture, renewable energy and alternative fuels, and computational engineering. He has supervised more than 130 M.Sc., Ph.D., and post-doctoral students, published more than 500 refereed articles, lectured extensively around the World, and consulted for the aerospace, automotive, and energy industry. He is a Fellow of ASME and APS, and the Combustion Institute and associate fellow of AIAA. Among his awards are the KAUST Investigator Award, the ASME James Harry Potter Gold Medal, and the AIAA Propellant and Combustion Award.

All interested are welcome to join via the zoom link.

Abstract:

The design of soft, smart materials is at the onset of many developments in polymer physics, chemical physics, biophysics, and materials science research. Here, polymers are an important class of soft matter whose properties are dictated by large fluctuations. Because of this reason soft systems are ideal candidates for the flexible design of advanced materials.
At the same time it is very difficult to study these materials within the conventional experimental, theoretical and/or computational setups.

In this talk, the complementary molecular simulation and experimental investigations will be presented with an aim to establish a microscopic understanding of some soft materials.In particular, two distinct cases will be discussed: The first case is related to the switchable responsiveness of (bio-)polymer solvation. The second case deals with the tuning of morphology, mechanics and its links to the thermal transport of solid polymers and molecular (CNT) forests.

[1] D. Mukherji, C. M. Marques, and K. Kremer, Annual Review of Condensed Matter Physics 11, 271 (2020)
[2] D. Mukherji, C. M. Marques, and K. Kremer, Nature Comm. 5, 4882 (2014)
[3] D. Mukherji, C. M. Marques, T. Stuehn, and K. Kremer, Nature Comm. 8, 1374 (2017)
[4] Y. Zhao, M. K. Singh, K. Kremer, R. Cortes-Huerto, and D. Mukherji, Macromolecules 53, 2101 (2020)
[5] D. Bruns, T. E. de Oliveira, J. Rottler, and D. Mukherji, Macromolecules 52, 5510 (2019)
[6] C. Ruscher, J. Rottler, C. E. Boot, M. J. MacLachlan, and D. Mukherji, Physical Review Materials 3, 125604 (2019)
[7] A. Bhardwaj, A. S. Phani, A. Nojeh, and D. Mukherji, arXiv 2005.10685 (2020)

Bio-sketch:

Dr. Debashish Mukherji's early education is from the Banaras Hindu University, Varanasi. He completed his doctoral degree in Physics from The University of Western Ontario, Canada, in 2008. He was a post-doctoral fellow at the Army Research Laboratory-Drexel Materials Center of Excellence in the United States during 2008-2010. He was also a PDF and then Project Coordinator at the Max Planck Institute for Polymer Research in Germany from 2010-2018. Currently, he is a Senior Scientist at the newly founded Quantum Matter Institute at the University of British Columbia in Vancouver, Canada.

His research interests include multiscale simulation in soft matter and materials science, structure-property relations of polymers, mechanical and thermal properties of advanced functional materials, and (bio-)macromolecular solvation thermodynamics.

All interested are welcome to join via the zoom link.

Abstract:

Multi-scale methods have been an important aspect in the field of engineering. Spatial multi-scale methods are used extensively for the determination of quantities of interest for heterogeneous continua, especially for alloys, porous media, composites and such others. As far as temporal multi-scale methods are concerned, they are used to simulate fatigue behaviour by avoiding cycle-by-cycle simulations. Both the cases are predicated on the fact that classical mono-scale methods require too fine FE mesh or too many time steps that can be computationally impossible, especially for non-linear material behaviour. The current work presents homogenisation technique based on asymptotic expansion for coupled elasto-viscoplastic-damage for heterogeneous medium, and for coupled thermo-elasto-viscoplastic-damage for combined cycle fatigue (CCF) loading. CCF loading basically involves high frequency low amplitude fluctuations (micro-cycles) embedded in low frequency high amplitude cycles (macro-cycles). A multi-scale technique has been used, which is based on separating the scale of interest (space/time) into a macro-scale and a micro-scale. The micro-scale represent the fast evolution in time (can be considered as micro-cycles) or the microscopic unit-cells in space. The macro-scale represent the slow evolution in time or the macroscopic structure in space. Based on asymptotic expansion and classical theory of numerical homogenisation, the problem eventually is separated into a macroscopic problem which involves the resolution of the homogenised quantities of interest, and a microscopic problem to evaluate their residual counterparts. Such a framework avoid cycle-by-cycle simulation of micro-cycles and they are calculated only at the macroscopic time points. For the spatial case, homogenisation technique avoids simulations of all repetitive unit-cells and they are calculated only at the macroscopic Gauss points.

Bio-sketch:

Dr. Mainak Bhattacharyya is currently working as a post-doctoral researcher at ENS Paris-Saclay, France. He received his B. Tech in Mechanical Engineering from Jadavpur University in 2011. Thereafter, he received his Masters in Applied Mechanics in IIT Madras, India. In 2013, he joined GKN Aerospace India located in Bangalore, India as a post graduate engineer. In 2014 he moved to Hannover, Germany to pursue his doctoral studies which culminated in a joint doctoral project work between Leibniz University Hannover, Germany and University Paris-Saclay, France. He defended is thesis in 2018, receiving a Doctor of Engineering from the Faculty of Civil Engineering, Leibniz University Hannover, Germany and a Doctor in Solid Mechanics from University Paris-Saclay. His first post-doc was at the National Institute of Applied Science of Lyon, France, and his second post doc was at ENS Paris-Saclay, University Paris-Saclay, France from 2019. His current research interests are in the field of continuum damage, reduced order modelling, multi-scale methods.

Abstract:

This seminar will discuss a quick method to draw inlet and outlet velocity diagrams for axial-flow compressors and turbines directly using their key performance parameters: the flow coefficient, the blade loading coefficient, and the degree of reaction or simply reaction. In the conceptual and preliminary aerodynamic designs of these turbomachines, designers will find the method extremely helpful in graphically determining all parameters of blade inlet and outlet velocity triangles along a streamline of constant radius and constant blade velocity. Exact equations to compute these parameters will also be presented.

Bio-sketch:

Dr. Bijay Sultanian has international experience in gas turbine aerothermodynamics, heat transfer (airfoil internal and film cooling), secondary air systems, and Computational Fluid Dynamics (CFD). Dr. Sultanian is Founder & Managing Member of Takaniki Communications, LLC. During his 30+ years in the gas turbine industry, Dr. Sultanian has worked in and led technical teams at a number of organizations, including Allison Gas Turbines (now Rolls-Royce), GE Aircraft Engines (now GE Aviation), GE Power Generation (now GE Power), and Siemens Energy (now Siemens Power & Gas). As an adjunct professor, he taught graduate courses on turbomachinery and intermediate fluid mechanics at the University of Central Florida for ten years. During 1971-81, he made landmark contributions toward the design and development of India’s first liquid rocket engine for the surface-to-air missile Prithvi and the first numerical heat transfer model of steel ingots for optimal operations of soaking pits in India’s steel plants. Dr. Sultanian is a Life Fellow of the American Society of Mechanical Engineers, a registered Professional Engineer in the State of Ohio, and an Emeritus Member of Sigma Xi, The Scientific Research Society. He is the author of Fluid Mechanics: An Intermediate Approach, Gas Turbines: Internal Flow Systems Modeling, and Logan’s Turbomachinery: Flowpath Design and Performance Fundamentals, Third Edition. He received BTech in mechanical engineering from the IIT Kanpur in 1971. Thereafter he obtained MSME from the IIT Madras; PhD in mechanical engineering from the Arizona State University; and MBA from the Lally School of Management and Technology at Rensselaer Polytechnic Institute, Troy.

Abstract:

Over the past decade, digital microfluidics has emerged as a promising fluid handling technology. It involves the generation and manipulation of discrete volumes of liquid inside microdevices, including micro and mini-channels and junctions. The digital microfluidics platform offers advantages of small sample size, reagent volume, speed of response, and high sensitivity due to higher precision and selectivity of the process. Beside this, miniaturization also allows increased automation and parallelization, which opens the way to screening and systematic testing of biological fluids. The main objective of the present work is to the development of a low-cost closed EWOD based digital microfluidics (DMF) platform for the analysis of droplet motion and deformation subjected to an external electric field. EWOD is a promising technique for manipulation of droplets in DMF due to its portability, high automation, high sensitivity, flexibility, reprogrammability, and simple device fabrication. It exploits changes in the wetting behavior of a conducting/polarized droplet placed on a dielectric surface, modified by the application of an electric field across the dielectric below the droplet. In this technology, nanoliter to microliter size droplets of samples and reagents are moved, split, merged, and mixed. In this work, the electronic interfaces are designed and fabricated to control a variety of fundamental droplet operations. The circuit design includes a high voltage control unit (0-300VDC). Bottom electrode patterns are fabricated using Printed Circuit Board (PCB) technology to make it easily accessible and less expensive. The use of Polypropylene (PP) as a dielectric as well as hydrophobic material in the EWOD device is not only introduces a simpler approach for the fabrication of the device but also makes it less costly. The basic fluidics operation intended on this system includes droplet motion and droplet merging. The work will help to introduce the EWOD system to existing LOC applications and provide a platform for the development of new research ideas.

Bio-sketch:

Dr. Vandana Jain is an Institute Post-Doctoral Fellow in the department of Mechanical Engineering at IIT Kanpur. She works in the area of microfluidic and EWOD based droplet system. In her research so far, she has proposed a low-cost solution in EWOD system designing, which can be useful in various biomedical applications. Her recent work aims to investigate the effect of the electric field in droplet deformation and transportation. She received her Ph.D. in the Center for VLSI and Nanotechnology, VNIT, Nagpur (2018), and M.Tech in Opto −Electronics. She is a member of IEEE.

Abstract:

The size optimization of electronic devices requires new approaches to the study of heat and mass transfer at microscale. In particular, the advancement in high performance heat exchangers, vapor chambers and heat pipes with microscale passages stimulates also development of a new fundamental knowledge of the processes with phase change. More refined experimental approaches are needed in order to probe interfacial conditions during the phase change. The talk deals with the temperature jump and Knudsen layer effects, where the continuum equations are no longer valid and the kinetic approaches should be used. The measurements were carried out using a microthermocouple with characteristic size of 2–3 μm. Temperature jumps were recorded at the interface, which increases with increasing heat flux density and the modes with both a positive and a negative jumps, as well as with the absence of a temperature jump, were recorded for the first time. The experiments are well described qualitatively with kinetic theory and Onsager-Casimir relations.

About the speaker:

Elizaveta Gatapova is a Senior Researcher at Kutateladze Institute of Thermophysics in Novosibirsk, Russia. She received her Ph.D. from Kutateladze Institute of Thermophysics in 2005 on the topic of application of shear-driven liquid films to cooling technology. Her current research broadly focuses on thermal management of electronics. She is interested in the fundamentals of the following: evaporation and heat transfer in microsystems, non-equilibrium effects at the liquid-vapor interface, wettability of nanostructured surfaces, contact line dynamics and rupture of thin liquid films. She has 6 patents and authored more than 60 publications. Her investigations were supported by the President of the Russian Federation in 2007, 2009 and 2012. Dr Gatapova is a recipient of INTAS (EU) and BELSPO (Belgium) Fellowships, several awards for young scientist and Academina award for women in science from Siberian Branch of the Russian Academy of Sciences and INTEL. She is PI of several national and cooperative projects. She is expert of the European Commission research and innovation programs and several Russian funds.

Abstract:

Regenerated cellulose fibers are produced by dissolving wood pulp, followed by regenerating it into fiber form. These bio-derived fibers are widely used in industry. Industrially, two processes are used to prepare such fibers. The most widely practised is the Viscose process, that uses environmentally hazardous solvents such as carbon disulphide. The more recent Lyocell process eliminates the use of carbon disulphide and is water based. There are differences in the properties of fibers produced using these processes. Therefore, the microstructure generated during the regeneration process greatly influences the properties. My talk will focus on developing an understanding of structure-property relations in semicrystalline fibers in general, and regenerated cellulose in particular. In the first part, I will describe a minimal model that describes the mechanical response of semicrystalline polymer fibers. We demonstrate that polymer fibers, including natural silk and synthetic fibers exhibit universal viscoelastic response. A simple phenomenological model accurately describes this data and provides insights into the microstructural origins of the fiber response. This model invokes only crystal-amorphous coexistence and no other features of the semicrystalline microstructure. Yet, it can successfully model the mechanical response of a wide variety of polymer fibers. In the second part of the talk, I will describe the application of this model to regenerated cellulose fibers prepared using Viscose and Lyocell processes. I will also describe a method to characterize the microvoids in Lyocell and Viscose fibers.

About the speaker:

Guruswamy Kumaraswamy is a Professor of Chemical Engineering at IIT-Bombay, Mumbai since October 2019. He received a BTech in Chemical Engineering from IITB in 1994, followed by an MS (1996) and PhD (2000) in Chemical Engineering from the California Institute of Technology. He spent a year as a VW Postdoctoral Fellow at the Max Planck Institute for Colloids and Interfaces. From 2001-2019, he was a scientist in the Polymer Science and Engineering Division at the CSIR-National Chemical Laboratory in Pune. Guru’s work focuses on controlling structure and investigating structure-property relations in soft matter systems. These systems range from polymers to surfactants and lipids and colloids. He collaborates extensively with industry and has worked with companies in India and abroad in the area of polymers, healthcare, personal care, waste valorization, etc. Recognitions for his work include the CSIR Young Scientist Award, the NCL Scientist of the Year Award and election to the Fellowship of the American Physical Society and the INAE. Guru is also passionate about science outreach to school students and in the last ten years, he has been associated with a volunteer group called the Exciting Science Group.

Abstract:

Free convective heat transfer within enclosures is a heavily researched area due to its natural occurrence in many real-world applications such as double-glazed windows, solar energy flat-plate collectors, nuclear reactors, and building enclosures. In the present study, heat transfer measurements and flow visualization are carried out for high-Rayleigh-number thermal convection in horizontal and tilted rectangular enclosures. Firstly, the effect of sidewall conductance heat loss on Nusselt number is examined. This thermal conductance through the sidewalls can significantly alter the Nusselt number (Nu) – Rayleigh number (Ra) correlation for horizontal enclosures (or, Rayleigh-Bénard convection), which is traditionally modeled by assuming a linear temperature profile along the sidewalls. Experiments (using three horizontal cubical enclosures, each made of different sidewall materials) revealed a higher difference between sidewall-uncorrected and sidewall-corrected Nusselt numbers than that obtained using a traditional model. A semi-analytical model and an empirical model were proposed to help future researchers predict and correct for this issue. Additionally, the experimental results were utilized to extrapolate and estimate Nusselt numbers for an ideal zero-thermal-conductivity sidewalls case. The second set of experiments is carried out to determine correlating equations for Nusselt number in terms of the studied variables for the horizontal and tilted enclosures. For the horizontal enclosure problem, sidewall-corrected Nusselt numbers were found to closely follow the classical 1/3rd scaling relation, which is different from the often reported 2/7th scaling relation for same range of Rayleigh numbers. For tilted enclosure, experiments revealed two noteworthy observations: (i) Nusselt number decreased monotonically with increase in tilting angle and (ii) for any tilting angle and Rayleigh number, Nusselt number followed a decreasing trend with increase in aspect ratio, which gradually amplified as tilting angle increased. The z-type shadowgraph flow visualization experiments, employed to characterize buoyant flow behavior at various angles of inclination, confirm the observed heat transfer trends.

About the speaker:

Dr. Umesh Madanan is a recent Ph.D. graduate in Mechanical Engineering (2019) from University of Minnesota, where he experimentally studied high-Rayleigh-number thermal convection in enclosures under the guidance of Dr. Richard J. Goldstein. He obtained his Master’s degree in Mechanical Engineering (2012) from Indian Institute of Technology Madras and Bachelor’s in Mechanical Engineering with honors from University of Calicut (2007). In the intermediate years between his academic pursuits, he also spent a few years gaining industrial experience. He worked at General Electric Power and Water, Bengaluru (2012-14) as an Edison Engineer. He also worked as an Assistant Manager in the Product Development division at Mahindra & Mahindra Ltd., Nashik between the years 2007 and 2009. His current research interests include experimental heat transfer, free convective heat transfer, porous-media heat transfer, and two-phase flows.

Abstract:

In this seminar, first, a general higher-order theory for open and closed curved rods and tubes using a novel curvilinear cylindrical coordinate system for the general hyperelastic material model will be presented. The impetus for this study, in contrast to the classical Cosserat rod theories, comes from the need to study bulging and other deformation of tubes (such as arterial walls). To analyze such problems, a novel generalized curvilinear cylindrical coordinate system is introduced in the reference configuration of the rod. This coordinate system is based on a new generalized hybrid frame that contains the well-known orthonormal moving frames of Frenet and Bishop as special cases. Such a coordinate system provides a geometric mapping system to map very complex geometries of the curved tubes with a reference curve (including any general closed curves) having continuous tangent and hence, can be used for analyzing any general rod or pipe-like 3-D structures with variable cross-section (e.g., artery or vein). The displacement field of the cross-section of the structure is approximated by general basis functions in the polar coordinates in the normal plane, which enables this rod theory to analyzethe response to any general loading condition applied to the curved structure. The governing equation is obtained using the virtual work principle for a general material response and presented in terms of generalized displacement variables and generalized moments over the cross-section of the 3-D structure. This results in a system of ordinary differential equations for quantities that are integrated across the cross-section (as is to be expected for any rod theory), which is solved using the finite element method. Furthermore, I will briefly present the general higher-order shell theory for hyperelastic material using Cartan’s moving frame This shell theory is capable of analyzing large deformation of arbitrarily curved thin or thick shell structures. In both the rod and shell theories, Cartan’s moving frame is used in contrast to the commonly used natural covariant frame, which makes the formulations and their numerical models computationally very efficient. Various numerical examples will be presented, illustrating both theories. Further, I will present my future research plan and teaching interests, followed by conclusions.

About the speaker:

Dr. Archana Arbind is a post-doctoral research associate in the department of mechanical engineering at Texas A&M University, College Station, USA. She works in the area of computational and applied mechanics. In her research so far, she has proposed various higher-order theories for beam, plates, rod, and shell in classical (nonlinear material) and Cosserat (rotation gradient theory) continuum. Her recent work aims to develop an efficient software tool to solve problems in bio-mechanics and soft material applications. She has presented her recent works in rod and shell theories in the World Congress in Computational Mechanics, 2018 and US National Congress in Computational Mechanics, 2019, respectively, with travel grant support from the conferences. She is also the recipient of Aruna and J. N. Reddy Distinguished Fellow in Computational Mechanics, from the Department of Mechanical Engineering, Texas A&M University. She holds MS (civil engineering) and Ph.D. (mechanical engineering) degrees from Texas A&M University, College Station, USA and B. Tech. degree from IIT Guwahati, India.

Abstract:

Vibration modes are orthogonal to the vibration field. Similarly, sound radiation modes are orthogonal to the sound radiation field. Therefore, attenuating the amplitude of sound radiation modes can give guarantee of reduction of sound radiation. This method of attenuating sound is called “Active Structural Acoustic Control (ASAC)”. However, this procedure has two biggest challenges, that is, “designing of specific actuators” and “finding optimal error quantity to be attenuated”. In this talk, I will speak about these two challenges in detail and implementation of ASAC on sandwich structures. Also, I will touch upon little bit on my current work at ABB.

About the speaker:

Kiran Chandra Sahu is working as a Scientist in ABB Power Grids Sweden. He did his PhD and Postdoctoral studies from Aalto University (Finland) and NTNU (Norway), respectively. He finished his undergraduate and master’s studies in Mechanical Engineering from University College of Engineering Burla and IIT Guwahati, respectively. Immediately after master’s study, he went to Finland with a Marie Curie fellowship to work as a Research Scientist at Technical Research Centre of Finland (VTT). During this stint, he visited various European institutes such as KTH (Stockholm), KU Leuven (Belgium), CNAM (Paris) and Centro Ricerche Fiat (Italy) etc.

Abstract:

Networks are ubiquitous and often at the heart of fundamental research in science and engineering, from the Internet, to social networks, bio-chemical reaction networks, transportation networks, power networks, and pharmacology networks that analyze chemical and clinical properties of drug-like molecules. In this talk, I will present some recently developed methods on analyzing such complex network systems, particularly from the point of view of optimization and control theory. In the first part of the talk, I will describe novel fixed-time convergent algorithms for convex optimization and its application to distributed optimization, and variational inequality problems. Many practical applications, such as, networked robotics, sensor networks, economic dispatch in power systems, often undergo frequent and severe changes in operating conditions, and thus require fast solutions irrespective of the initial conditions. Tools from fixed-time Lyapunov theory are leveraged for achieving global fixed-time convergence guarantees. In the second part of the talk, I will look into designing control algorithms that scale efficiently from single agent to multiple agents. Communication agnostic control framework for microgrid systems will be of interest. Dynamical similarity among multiple agents (power converters) is exploited to model the entire microgrid as an equivalent single converter system. Moreover, various performance objectives, such as, voltage regulation and robust stability of the overall microgrid system can be analyzed in terms of the performance objectives of the single converter system.

About the speaker:

Mayank Baranwal is a postdoctoral scholar in the Department of Electrical Engineering and Computer Science at the University of Michigan, Ann Arbor. He obtained his Bachelor’s in Mechanical Engineering in 2011 from Indian Institute of Technology, Kanpur, and MS in Mechanical Science and Engineering in 2014, MS in Mathematics in 2015 and PhD in Mechanical Science and engineering in 2018, all from the University of Illinois at Urbana-Champaign. His research interests are in modeling, optimization, control and inference in network systems with applications to distributed optimization, reduction of biochemical networks, transportation networks and control of microgrids.

Abstract:

The balance of material momentum, also known as impulse or pseudo momentum, is a concept in continuum mechanics whose utility is not always apparent. We will discuss the significance of this balance law for purely mechanical systems governed by an action, and its relation to the balance of physical momentum and energy in the bulk and at propagating interfaces. We will explore the implications of this concept on problems involving rods subjected to partial constraints.

About the speaker:

Harmeet Singh is working as a Post-doc Fellow at Ecole Polytechnique Federale de Lausanne Since Feb 2019. He completed his PhD from Virginia Tech University in Dec 2018 from the department of Engineering Mechanics. He did his M. Tech in Structural Engineering from IIT Kharagpur in 2012. Post this he worked in Airbus India for a couple of years. His research interests are in classical mechanics, geometry, dynamics of thin bodies, and elasticity.

Abstract:

Online design contests are conducted by organizations to gather a large number of ideas quickly. However, few systems exist to support online teams participating in design contests. Additionally, organizations find it difficult to process thousands of ideas efficiently. In this talk, I will talk about using optimization and machine learning methods to enable distributed teams of people to work together on design problems. Specifically, we will discuss three problems faced by organizations in gathering and processing ideas from distributed teams: 1) How does one form teams to evaluate design ideas? 2) How does one reliably measure the creativity of ideas? and 3) How does one filter high quality and diverse ideas out of hundreds of submissions? I will discuss how our matching, ranking, and novelty estimation algorithms help address these problems. The scientific and mathematical work done to answer these questions lay the foundations for representation, learning, and optimization of discrete items in Engineering Design. I will also briefly talk about research directions on AI-driven design for my lab at MIT.

About the speaker:

Faez Ahmed is a Post-doc Fellow at Northwestern University. Faez works at the intersection of optimization, machine learning, and engineering design. He completed his Ph.D. in Mechanical Engineering at the University of Maryland and did his undergraduate at IIT Kanpur. Prior to his Ph.D., he worked as a Reliability Engineer for Rio Tinto in Western Australia. He was a Future Faculty Fellow at the University of Maryland and recipient of the Kulkarni Fellowship. He is a member of the ACM Distinguished Speakers Committee and has ongoing collaborations with other non-profits, to educate the local community about computing and data science.

Abstract:

Water is essential to sustain human life, plants and the animal kingdom. As for human life, water is increasingly becoming a precious commodity for a variety of reasons. The scarcity of fresh water affects human life much more than anyone could ever have imagined. Water scarcity currently affects over 40% of the human population in the entire world, with an estimated 783 million people having no access to clean water. Alarming results of a study indicate that over 4 billion people live with severe water scarcity for at least one month every year; some of the severely affected regions of the world include advanced countries of the world as well

Technologies for obtaining water from conventional water bodies such as lakes, rivers and the oceans exist in the modern world, and is often supplemented by processes such as desalination and the use of recycled water. Despite these technologies, water distribution systems in the world are incapable of providing fresh water to satisfy the needs of rising human population. The changing global rainfall patterns, excessive drought, climate changes, man-made wastage of water due to poor planning and implementation schemes woefully contribute toward water scarcity. Water as a commodity is thus increasingly becoming a strategic resource, and its scarcity motivates the need to identify and develop technologies for alternate sources of water to feed and sustain life on this planet. In this background, droplet condensation of atmospheric water vapour – known as fog-harvesting is significant, and provides a source for generating water.

The seminar will introduce fog harvesting as a source for the production of water, and its development in few formats as available currently in the world. In tandem, a passive method initiated and proposed by IIT Kanpur is presented which will form the basis for research collaboration between IIT Kanpur and Curtin University, Australia.

About the speaker:

Dr. Ramesh Narayanaswamy is a Visiting Faculty in the Department of Mechanical Engineering, IIT Kanpur. He is currently Associate Professor of Mechanical Engineering at the School of Civil and Mechanical Engineering, Curtin University in Perth, Australia. His research interests are in the area of Heat Transfer.

Abstract:

This talk gives an Editor’s perspective on journal publishing. The talk will briefly introduce the goals of publishing followed by a detailed elucidation of manuscript preparation, highlighting along the way common pitfalls in a submission. The talk will also briefly cover author responsibilities and ethics followed by a discussion on the peer review process. The talk will end with key takeaways and some final tips.

About the speaker:

Dr. C. Balaji is currently a Professor in the Department of Mechanical Engineering at IIT Madras. He has over 25 years of experience in teaching and research. He has authored over 180 International Journal Publications and has supervised 29 PhD, 13 M.S and over 60 M.Tech thesis so far. He is a Swarnajayanthi fellow, Humboldt fellow and is also an elected fellow of INAE. He specializes in heat transfer, inverse problems, numerical weather prediction and data assimilation. He has authored 7 books and is currently the Editor-in-Chief of the International Journal of Thermal Sciences published by Elsevier.

Abstract:

Gas hydrate, is by far, the largest repository of methane existing on the planet. They are formed under low temperature and high-pressure conditions prevailing in the ocean floor or permafrost. The proposed methods for extracting methane include depressurization, thermal stimulation and chemical injection. These methods would typically involve setting up the well bores and other process equipment at the reservoir bed. Following which, the extraction procedure is carried out through the standalone or combination of any of the aforementioned techniques. The basic idea here is to destabilize the reservoir physical state and let the hydrate dissociate. This essentially disturbs the reservoir stability in terms of balance between reservoir pore pressures, overburden-under burden and tectonic stresses. The modelling of the stability aspects of the hydrate reservoirs is therefore significant. Poorly compacted or faulted reservoirs may undergo geomechanical failures. The modelling requires a detailed characterization of the sediment strength and the other physical properties such as stiffness and Poisson ratio followed by the determination of effective stress distribution in the given area. Hence, there exists a profound need to carefully study the geomechanical response of reservoirs under various production scenarios, which would certainly help in locating the potential failure zones and determining the safe-limit of the operation parameters.

About the speaker:

Dr Rahul Yadav obtained his PhD from IIT Madras in the year 2018 with a specialization in Radiation Heat Transfer and Optimization. In IIT Kanpur, he is associated with Gas Hydrate Research Group and their activities. He is interested in geomechanical features of the Indian reservoirs during the production process from numerical modelling and optimization point of view.

Abstract:

Soft tissues are complex materials whose functioning is governed by the micro-structure and composition of their constituents. Hence any change in the structure and properties in response to external stimuli like mechanical loading, and chemical reactions (oxidation and glycation) affects the functioning of the tissues, resulting in various pathological conditions. So, it is necessary to understand the change in the mechanical behavior of tissue, when it is exposed to different chemical environments. In the first part we develop structurally motivated phenomenological models within a thermodynamic framework to relate the chemical kinetics of oxidation to the change in the mechanical response of aorta in a systematic fashion

In the second part, we present the constitutive theory which incorporates the energy limiter to enable failure description of hyper-elastic solids. Traditional hyper-elastic constitutive models are developed to describe the mechanical response of intact material. So, these models satisfy the material stability requirement. Strong ellipticity condition, Baker-Ericksen inequalities, polyconvexity are different forms of material stability requirement. During earthquakes, rubber bearings used for seismic isolation of structures undergo large shear deformations due to horizontal motion of the ground and compression due to weight of structure and possible traffic. In this work, we predict the onset of cracks in rubber bearings under combined shear and compression via the loss of strong ellipticity of the constitutive model.

About the speaker:

Dr. P. Mythravaruni was a postdoctoral fellow with Prof. Konstantin Volokh at faculty of Civil and Environmental engineering, Technion-Israel Institute of Technology, Israel. She obtained her PhD in Mechanical Engineering, Machine design section from IIT Madras under the supervision of Prof.Parag Ravindran. She pursued her M.Tech under the supervision of Prof.Sumit Basu at IIT Kanpur. Her research areas of interest include Continuum Mechanics and Rheology of Complex Materials.

Abstract:

Acoustic wave propagation in a duct is governed by the Helmholtz equation, which is derived from the linearized fluctuating forms of the mass, momentum and energy balance equations. For 1-D domains, the Helmholtz equation is a second-order ordinary differential equation (ODE), while the fluctuating balance equations are all first-order ODEs. As a result, one needs two boundary conditions for the spatial pressure fluctuation pˆ(x) in order to solve the Helmholtz equation, while only one boundary condition each is needed for ρˆ, uˆ and pˆ in case of the fluctuating balance equations. Accordingly, this study was motivated by two principal objectives. The first was to develop the exact Neumann (or derivative) boundary condition at the inlet to a quasi 1D duct needed to solve the Helmholtz equation. Such an exact boundary condition would ensure that the spatial pressure fluctuations pˆ(x) obtained by solving the Helmholtz equation are identical to the pˆ(x) obtained through the solution of the fluctuating balance equations. The second principal objective was to determine the exact relationship between the density and pressure fluctuations, ρˆ and pˆ respectively, so that the ρˆ(x) calculated using the Helmholtz-equation pˆ(x) is again identical to the ρˆ(x) obtained by solving the fluctuating balance equations. The exact ρˆ-pˆ relation is also compared with the “classical” relation, namely ρˆ = ˆp/c¯ 2, enabling us to evaluate the accuracy of the latter. The Neumann boundary conditions and the ρˆ-pˆ relations were developed for five cases with axially uniform and non-uniform duct cross-sectional areas, as well as homogeneous and inhomogeneous mean flow properties such as the velocity, temperature, density and pressure. It is seen that the ρˆ = ˆp/c¯ 2 relation is valid only for the cases with uniform cross-sectional area and homogeneous mean properties. For the cases with uniform cross-section, inhomogeneous mean properties (with zero or uniform mean flow), the “classical” ρˆ relation suffers from significant errors both in amplitude and phase.

About the speaker:

Dr. Sarma L. Rani is a tenured Associate Professor in the MAE Department at the University of Alabama in Huntsville. His research focuses on the computational and theoretical investigations of fundamental questions in three principal areas: (1) turbulent flows laden with disperse spherical and complex-shaped particles, (2) acoustic wave propagation and combustion instabilities in premixed combustion systems, and (3) development of low-dissipation, high-order shock-capturing numerical schemes for compressible flows. He has graduated 5 Ph.D. and 4 Masters students. He is the recipient of the 2016 College of Engineering Outstanding Junior Faculty Award, as well as the 2017 UAH College of Engineering Outstanding Faculty Award.

Abstract:

Electricity generation via thermal route using solar energy is a clean and promising way which has vast potential in India. Optimum layouts of collectors in solar concentrators' fields yielding minimum cost of electricity are need of the hour. The work focuses on development of cost optimum solutions for line focusing solar concentrators' fields- Parabolic Trough Collector (PTC), Linear Fresnel Reflector (LFR) and Compact Linear Fresnel Reflector (CLFR). Software tool for analyzing the performance of the solar fields with different designs (involving length, width, spacing and number of collectors, receiver height, latitude, longitude and declination of earth) is developed as an end product which will benefit researchers, industries and government in their research work, business, energy solutions, environment and policies.

About the speaker:

Dr. Vashi Mant Sharma is an INSPIRE Faculty Fellow in the department of Mechanical Engineering, Indian Institute of Technology Kanpur since Jan 2017. He received his Master's and PhD in 2009 and 2014 from IIT Bombay. Post his PhD; he was a Postdoctoral Researcher in the Ministry of New & Renewable Energy’s Project from 2015 to 2016. His areas of interest are: Concentrating Solar Thermal, Optics of Concentrators, Thermal Energy Storage, and Renewable Energy.

Abstract:

Abstract: Additive manufacturing (AM) or 3D printing is maturing rapidly as a viable solution of make optimized parts for “real engineering” applications. What started as an amateurish persuasion has now evolved into a worldwide phenomenon that is touching industries from aerospace to industrial equipment to automotive to life science to energy & process, and others. The freedom of design that is achievable using AM process is un parallel in terms of reducing structural weight, reducing material cost, generating complex shapes and connections and introducing directional properties in a component. However, understanding of AM process and utilizing process parameters to optimize a design comes with many challenges. Currently, one of the emphasize is to use physics based realistic simulation to replicate the AM process numerically and relate process parameters to the concept of functional generative design that relates design with manufacturing process. Current work, through a typical build example, will discuss the following solutions on a digital platform: Generative Design, Process Planning, Process Simulation, Post-processing.

About the speaker:Dr. Arindam Chakraborty is a Vice President of Advanced Engineering at Virtual Integrated Analytics Solutions, USA. Dr. Chakraborty received his Ph.D.in Mechanical Engineering from the University of Iowa doing research in probabilistic fracture mechanics. He has over 12 years of combined academia and industry experience in solid mechanics and design, non-linear FEA, fatigue and fracture mechanics, reliability analysis, composite structures. Starting with Nuclear, he has working industries such as Oil & Gas, Aerospace, Life Science, and Hi-Tech. He is currently managing all simulation services at VIAS including business strategy and partnership development, technical hands-on with advanced FEA. He provides training in FFS, Fatigue and Fracture Mechanics, FEA, Scripting, Probabilistic Analysis. He is also involved with industry collaboration, technology development, regulatory compliance, business strategy development. Dr. Chakraborty is engaged with Pressure Vessels and Piping conference committees, chairs conference sessions, involved with ASME & API code committees and has published more than 25 journal and conference papers.

Abstract:

Abstract: Inflatable structures are preferable in several space and terrestrial applications and tunable devices. They are light, can be packed/stowed and deployed quickly, and easily tunable. In particular, an inflatable toroidal geometry has a number of applications. The finite inflation and stability of a toroidal membrane, inflated from a flat geometry, is discussed. The uninflated geometry consists of two identical equatorially bonded flat annular membranes which results a closed toroidal structure upon inflation. Two different hyperelastic material models, namely, Mooney-Rivlin model and Gent model, are used to describe the isotropic incompressible membrane material with a relaxed strain energy density function. The inflation problem involves both geometric and material nonlinearities. Wrinkling is observed along the outer equator of the torus at low inflation pressures. A pressure limit (snap-through) is found to exist which can be linked with the material and geometric parameters of the torus through an empirical relationship involving two universal constants. Based on the energy release rate calculations at the equatorial joints, the possibility of joint peeling is investigated. Inflatable toroidal membranes can be used as the outer rim of inflatable antennas, tunable lens, or inflatable reflectors. The stability of such structures depends on the stability of the inflated toroidal membranes subjected to radial forces at the interaction boundary from the inner members. The response of the inflated membrane against radial in-line force distribution along the inner equator is studied under two different forcing conditions, namely, constant pressure forcing and forcing with constant amount of enclosed gas. The first type of loading leads to wrinkling instability, whereas the second one results a pull-in instability of the torus beyond a critical force value. Though the symmetric geometry (both axisymmetry and existence of a plane of symmetry) of the inflatable structures is most common, but under certain conditions, symmetry may not exist due to loss of stability of the symmetric solution. The study of geometric symmetry breaking of the toroidal membrane is presented using perturbation technique. Beyond a critical level of pressurization, the torus undergoes a spontaneous symmetry breaking through a super-critical pitchfork bifurcation, which is later restored back by a reverse sub-critical pitchfork bifurcation. The corresponding asymmetric shapes and the symmetry breaking zones are marked. The contact problem of an inflated torus with rigid flat plates are of practical interest in modelling air springs or vibration absorbers, where the inflated membrane acts as a non-linear spring whose stiffness can be tuned by changing the air pressure of the closed membrane. The contact might be of different types such as frictionless, frictional, and adhesive contact. The frictionless contact problem of the inflated torus pressed between two flat rigid plates is analyzed. The nonuniform stretching of the membrane is reported in the contact zone unlike the frictionless contact problem for the spherical and cylindrical geometry. The effect of temperature variation on the inflation pressure and inflated geometry of the toroidal hyperelastic membrane is discussed.

About the speaker:Dr. Soham Roychoudhary is an Assistant Professor in the School of Mechanical Sciences, Indian Institute of Technology Bhubaneswar. He received his M. Tech and PhD in 2014 and 2019 from IIT Kharagpur. Post his PhD, he was a DST Inspire Faculty Fellow in the Mechanical Engg. Department, IIT Kanpur from April to July 2019. His areas of interest are: Inflatable Membrane Structures, Nonlinear Elasticity, Structural Stability, Continuum Mechanics.

Abstract:

Abstract: Marine and hydro-kinetic (MHK) energy hold promise to become significant contributor towards sustainable energy generation. Despite the promise, commercialization of MHK energy technologies is still in the development stage. While many simplified models for MHK site resource-assessment exist, more research can enable efficient energy extraction from identified MHK sites. A marine energy company named Verdant Power Inc. was granted first US federal license to install up to 30 axial hydrokinetic turbines in the East River in New York City under what came to be known as Roosevelt Island Tidal Energy (RITE) project. In this seminar, I will discuss the research done for the real-life tidal energy project, the RITE project, using high-fidelity numerical simulations.

A laboratory-scale wake analysis was first done for three turbines in a TriFrame configuration where the turbines were mounted together at the apexes of a triangular frame. Large-eddy simulation (LES) was employed to simulate turbine-turbine wake interactions in the TriFrame. The wakes of the TriFrame turbines is compared with that of an isolated single turbine wake in order to further illustrate how the TriFrame configuration affects the wake characteristics in an array. Next, a 30-turbine array was simulated in the New York City’s East River with natural bathymetry at field scale. To this end, optimized data-structures and efficient modules were developed for a local mesh-refinement based LES framework. The new flow solver, coupled with a sharp-interface immersed boundary method, enabled multi-resolution 3D simulations on locally refined grids at relatively lower computational cost. The results are analyzed in terms of the wake recovery and overall wake dynamics in the array.

About the speaker:Dr. Sourabh Chowdhary is doing postdoctoral research for Argonne National Laboratory. He received B.Tech.-M.Tech. dual degree from Indian Institute of Technology Kanpur and his Ph.D. in Mechanical Engineering from University of Minnesota. His research interests include computational fluid dynamics, large-scale simulations, environmental flows, biological flows and high-performance computing. His current research focusing on the development of a high-performance scientific code called “FLASH” will enable exa-scale simulations. Saurabh is passionate about use of computational science as a predictive tool to solve modern-day scientific and engineering problems.

Abstract:

Abstract: Continuum hypothesis based properties; for example, elastic moduli of a material/structure at small length scales can be found using molecular mechanics or dynamics. While doing so one makes a few key assumptions and develops what are called as equivalent continuum structures (ECSs). Accuracy of the derived continuum quantities for a given structure thus depends strongly on its ECS. In this talk I will first present development of ECS for single-walled carbon nanotubes (SWCNTs) based on MM3 potential employing classical theories of linear vibrations and show an instances when the developed ECS fails. Subsequently, results from two methods leading to conflicting values of critical buckling strain in SWCNTs under compression and torsion will be presented. Lastly, I will present some recent results on instability in a carbon nanocone when it is pulled out from a stack.

Abstract:

Proposed in the year 1965 by two English statisticians, the Nelder-Mead simplex direct search method was suitably placed to cater to the growing interest of computer solution of the highly nonlinear optimization problems. The method is based on a simple idea according to which a geometrical shape 'adapts itself to the local landscape' while searching for the minimum of a given function. Because of its simplicity, the method gained immense popularity among the researchers/practitioners of almost every possible field of science and engineering, so much so that it has become one of the most cited works in the history of optimization algorithms. However, the original method has some serious flaws and limitations. In this talk, we will come across some of these limitations and will also discuss the modifications suggested to overcome these limitations.

About the speaker:

Dr Vivek Kumar Mehta got his Bachelor's degree in Engg from Bhilai Institute of Technology Durg in 2003, M.Tech. degree from IIT Kanpur in 2005 and Ph.D. degree from IIT Kanpur in 2013. His Master's thesis was on optimal design of parallel manipulators and doctoral thesis on multi-objective optimization. His research interests are Optimization, Robotics and Science Education. Besides his research papers, he has authored and translated several popular science articles and social/humanitarian articles in Hindi. During 2013-14 and since 2016, he has been a faculty member in Tezpur Central University, Assam. Dr. Mehta was a Fellow of Eklavya, Bhopal from April 2015 to September 2016.

Abstract:

Composite materials are seeing increasing uses in several structural components. However, prediction capabilities of composite properties and performance are not yet matured. With the advent of modern experimental facilities and high performance computational capabilities, it is possible to enhance and develop computational tools accounting for the properties at microscale (fiber, fibermatrix interface). These capabilities can reduce the cost of testing for certification and enable virtual testing of composites with synergetic utility of experimental data. In this talk, multiscale characterization and modeling to predict macroscale behavior of carbon fiber reinforced laminates will be presented. The methodology accounts for the experimentally measured properties of matrix and fiber-matrix interface at microscale and prediction at macroscale behavior. Apart from classical fiber reinforced composites, bioinspired/architectured composites are being developed to achieve enhanced performance that can exceed the performance limits of their constituents or can achieve otherwise competing properties (e.g. stiffness and damping). With state of the art manufacturing techniques (e.g. 3D printing), such micro-architectured composites can be fabricated. Design and characterization of a novel micro-architectured composite will be presented. This composite is designed based on hexagonal symmetry of the building blocks to provide in-plane isotropic behavior and simultaneously high stiffness and damping.

About the speaker:

Sandip Haldar is postdoctoral researcher at the University of Central Florida, Orlando. Sandip worked at the University of Toronto, Canada and at the IMDEA Materials Institute, Madrid, Spain as a Research Associate following PhD from University of Maryland, College Park, USA. He obtained MSc (Engg) from Indian Institute of Science, Bangalore and BE in Mechanical Engineering from Bengal Engineering and Science University, Shibpur. His areas of research include characterization and modeling of composite materials including fiber reinforced composite, sandwich structures and designing novel composites e.g. bioinspired, architectured composites that can potentially exceed the existing performance limit of the engineering materials. Currently, he works on the mechanics of multi-layered Thermal Barrier Coatings (TBCs) and stress sensing polymer nanocomposites.

Abstract:

Soft and highly strain hardening metals like Ni, Al, Ta and stainless steels, are notoriously difficult to cut, earning them the moniker “gummy”. This difficulty is well-known for its commercial implications, yet its origins have remained largely speculative. This talk presents high-speed in situ investigations of this problem in two parts. In the first, we unveil the occurrence of a highly unsteady plastic flow mode, termed sinuous flow, as the cause of this difficulty. Sinuous flow arises due to a surface plastic buckling instability and is characterized by repeated material folding, large local strains (>10) and energy dissipation. The nature of this flow, its dependence on material properties, and manifestation across metals are directly observed. In the second part, we demonstrate how plastic flow can be perturbed using mechanochemistry. A suitable chemical medium applied to the metal surface causes a local ductile-to-brittle transition by coupling plastic instabilities with interface energetics. Consequently, chip formation now occurs either via a periodic fracture instability or smooth laminar flow, with near absence of defects on the cut surface and significantly lower energy dissipation (<50%). The transition in flow is also reflected in the morphologies of the resulting metal chips. Two such controllable mechanochemical effects will be discussed – one material-independent and another tailored to specific metal systems. The benign nature of the chemical media involved presents exciting opportunities for fundamentally enhancing cutting and deformation processing of metals in industrial settings.

About the speaker:

Koushik Viswanathan is an Assistant Professor in the Department of Mechanical Engineering at the Indian Institute of Science (IISc), Bangalore. Prior to joining the institute in 2018, he worked as a post-doctoral researcher at the Center for Materials Processing and Tribology at Purdue University. He obtained his PhD and MS degrees from Purdue University in 2015 and 2014, respectively. His research interests include manufacturing science, experimental mechanics, metrology and applied mathematics.

Abstract:

Microscopic quantum mechanical interactions among heat carriers called phonons govern the macroscopic thermal properties of semiconducting and electrically insulating crystalline solids, which find applications in thermal management of electronics, thermal barrier coatings and thermoelectric modules. In this talk, I will describe my recent work on how our newly developed first-principles computational framework to predict these microscopic interactions among phonons unveils a new paradigm for heat conduction in several of these materials. As an example, I will describe a curious case of heat conduction in boron arsenide (BAs), where the lowest order interactions involving three phonons are unusually weak and higher-order scattering among four phonons affects the thermal conductivity significantly, in stark contrast with several other semiconductors such as silicon and diamond [1]. I will show that this competition between three and four phonon scattering can be exquisitely tuned with the application of hydrostatic pressure, resulting in an unusual non-monotonic pressure dependence of the thermal conductivity in BAs unlike in most other materials [2]. I will also briefly describe my prior experimental effort to probe the scattering of phonons at atomically rough surfaces of a nanoscale silicon film, where they showed extreme sensitivity to the changes in surface roughness of just a few atomic planes [3]. Finally, I will motivate my current work and future research directions of consolidating these experimental and computational advances to probe the interactions of phonons with other forms of energy carriers such as electrons in semiconductors and metals, at high temperatures and extreme environmental conditions. [1] Fei Tian, Bai Song, Xi Chen, Navaneetha K. Ravichandran et al., Science 361 (6402), 582-585, 2018 [2] Navaneetha K. Ravichandran & David Broido, Nature Communications 10 (827), 2019 [3] Navaneetha K. Ravichandran, Hang Zhang & Austin Minnich, Physical Review X 8 (4), 041004, 2018

About the speaker:

Dr. Ravichandran obtained his Dual Degree (B. Tech and M. Tech) in Mechanical Engineering from the Indian Institute of Technology, Madras. He obtained his Masters in Space Engineering and PhD in Mechanical Engineering from Caltech, working with Prof. Austin Minnich. For his PhD, he worked on experimentally investigating phonon boundary scattering in thin silicon membranes using the transient grating experiment. He is currently a postdoctoral fellow at Boston College. More: https://navaneethravichandran.gitlab.io/navaneetha-k-ravichandran/

Abstract:

In contrast to classical solid-solid contact, liquid-solid contact is governed by the contact line, where a contact angle can form and undergo hysteresis. Liquid-solid contact therefore requires additional contact algorithms that capture the contact state at the contact line. Altogether four contact algorithms are required in order to describe the general contact behavior between solids and liquids: frictionless surface contact, frictional surface contact, frictionless line contact and frictional line contact. For the latter, a new predictor-corrector algorithm is presented that enforces the contact conditions at the contact line and thus distinguish between the states of advancing, pinning and receding contact lines. The algorithms are discretized within a monolithic finite element formulation. Several numerical examples are presented focusing on rolling and sliding droplets. For quasi-static droplets, the interior medium follows a hydro-static pressure relation that does not require discretization. For dynamic droplets, the interior fluid flow is accounted for through the incompressible Navier-Stokes equations.

About the speaker:

Roger A. Sauer is an associate professor at the graduate school AICES at RWTH Aachen University working in the field of theoretical and computational mechanics. He is a civil engineering graduate from the Karlsruhe Institute of Technology (2002) and holds a PhD in mechanics from the University of California at Berkeley (2006). The research group of Dr. Sauer develops multifield theories and corresponding computational methods for the robust, efficient, and accurate simulation of interface phenomena, such as contact problems, shell formulations and fluid-structure interaction.

Abstract:

Multi phase (Two or more phases) flows are quite common in the process industry. In fact many process equipment are designed on the basis of Mixing or to create Separation. Use of computational tools and CFD is very well established in Aerospace and Automotive Industry. Process Industry have been late adopters of such technology due to inherent complex nature of the fluid flow. In this talk, I plan to showcase modeling challenges associated with designing and analyzing some industrial equipment and processes.

About the speaker:

Ashish completed his masters in Mechanical Engineering (with specialization in Fluid Mech and Thermal Sciences) from IIT Kanpur in the year 2000. His professional career started with ANSYS-FLUENT in support & consulting role. In 2007, Ashish co-founded Tridiagonal Solutions. Over last ten years, Tridiagonal has grown substantially to team of more than 100 engineers. With offices in India and US and its own products for process industry, Tridiagonal has become a brand of choice for Flow Modeling Services and Solutions. Ashish has trained and groomed more than 200 engineers in the fluids sector. His latest passion includes creation of application specific tools and deployment of open source technologies to democratize CFD.

Abstract:

The pursuit of mimicking Natural systems has been a tireless effort with many successes but a daunting task ahead. A new perspective to engineer the very evident branched/fractal-like shapes spanning multiple scales and intricate web of microfluidic channel will be presented. These structures are established to be more effective in the literature for mass and heat transport applications and promise many more. Control over Saffman-Taylor instability which otherwise randomly rearranges viscous fluid in a ’lifted Hele- Shaw cell’ is exercised for the same. The proposed fluid shaping control employs anisotropies on cell plates, to shape a stretched fluid film into a network of ordered multiscale tree-like patterns and well defined webs/meshes mimicking various biological systems. The proposed control produces in a robust and repeated fashion, structures which otherwise are completely non-characteristic to this process. Moreover spontaneous manufacturing of families of wide variety of structures can be done over micro and very large scale in a period of few seconds. Thus the proposed method establishes a solid foundation to a new pathway for engineering mulitscale structures for several scientific applications including fish gill mimicking, solar electrodes, organ-on-chip, capillary pumping, and so on. Apart from this, the talk will give brief overview of other activities going on in our Suman Mashruwala Advanced Microengineering laboratory.

About the speaker:

Prasanna’s current research focuses on the area of polymer and ceramics 3D micro-printing, control of fluid instabilities for Spontaneous Multiscale Manufacturing (SMM), dynamics and control of ultra flexible mechanism systems for applications in micro-printing, micro-fluidics, medical robotics, products, and devices. He has received his PhD at Rice University, Texas in 2001, MTech at IIT Bombay in 1996 all in mechanical engineering. He was pioneer in setting up non-VLSI based 3D digital microfabrication and characterisation facility in the Department of Mechanical Engineering at IIT Bombay. He has been researching the area of 3D microfabrication technology for more than 16 years and has successfully developed in-house technologies of Microstereolithography, Bulk lithography (BL), Spontaneous Multi-scale Manufacturing (SMM) using fluid instabilities which have resulted in several publications and patents. Technologies developed in Prasanna's laboratory are transferred to and in use with ISRO (Slosh characterisation), OFB (Safe and Arm Device), a few companies (micromilling, 3D microprinting). Among other he is recipient of Robert Lawny Patten award at Rice University, Best faculty award at ME IITB, Issac fellowship, and FEI foundation award 2019 for a technology licensed to Strategi Automation.

Abstract:

Modern computing infrastructures hold high promise for scientific computing, enabling high resolution simulations which were not possible with previous generation of computers. Adaptive Mesh Refinement (AMR) is a technique which allows specific regions of interest in the domain to be resolved locally. In this talk, I will present capabilities of an AMR based multi-physics code, FLASH. FLASH is a high-performance application code developed at University of Chicago and capable of solving many different types of problems. In the next generation of FLASH, we are adopting AMReX library to enable octree based block-structured AMR. We are also working with Tokyo Institute of Technology researchers to enable architecture-specific code optimizations in FLASH. I will also present results from an applied study demonstrating the usefulness of AMR in the field of tidal energy. An AMR-LES (large-eddy simulation) based framework is used to model the flow in a section of the East River of New York City with detailed river bathymetry and inset hydrokinetic turbines. Use of AMR allowed the simulation to be conducted at field-scale in a real-life marine environment reproducing the rich the site-specific flow dynamics. The results are analyzed in terms of the wake recovery and overall wake dynamics in the turbine array. This simulation helped the field-engineers at Verdant Power in developing the turbine-array layout for the Roosevelt Island Tidal Energy (RITE) project.

About the speaker:

Saurabh is a postdoctoral researcher at Argonne National Laboratory and University of Chicago. He received B.Tech. and M.Tech. from Indian Institute of Technology Kanpur and his Ph.D. in Mechanical Engineering from University of Minnesota in 2017. His research interests include computational fluid dynamics, large-scale simulations, high-performance computing, wind and hydrokinetic energy, biological flows and fluid dynamics in nature. His current research at Argonne focuses on development and use of a high-performance scientific code “FLASH”. Saurabh is passionate about use of computational science as a predictive tool to solve modern-day scientific and engineering problems.

Abstract:

Soft tissue damage is the primary outcome of injuries and musculoskeletal diseases, caused due to permanent deformation or rupture of the complex soft tissue structure. To date, the mechanics of soft tissue damage is poorly understood due to ethical and biosafety issues associated with mechanical testing of live human tissues, and low bio-fidelity (i.e., ability to simulate the mechanical properties of soft tissues) of surrogates such as animal skin, gels and silicones. This key gap in literature inhibits the development and testing of medical intervention techniques for effective soft tissue damage prevention. In this presentation, I will summarize the development and characterization of highly bio-fidelic soft tissue surrogates and review my prior works on the study of soft tissue damage at the structure and organ levels. An integrated model for testing of soft tissue damage interventions using the highly bio-fidelic surrogates is then proposed, targeting two major medical issues: Plantar Fasciitis and Hernia. I will discuss my current and future research plans, and conclude with the societal impact and collaboration opportunities with the local industry, students, and faculty at IIT Kanpur.

About the speaker:

Dr. Arnab Chanda is a Postdoctoral Research Scholar in the Department of Bioengineering at the University of Pittsburgh, USA. He holds a PhD in Aerospace Engineering and Mechanics from the University of Alabama, USA, and is also the founder of BIOFIT Technologies LLC. Arnab is interested in understanding the mechanics of soft tissue damage and their interaction with medical intervention (MI) technologies. To date, Arnab’s research has led to 1 Grant Funding, 7 US Patent Applications, 21 First-Author journal publications, and 7 conference papers. Arnab aims to continue his efforts in improving MI technologies for better patient outcomes, through research, teaching, and technology transfer.

Abstract:

Magnetohydrodynamics (MHD) broadly refers to the interaction of electrically conducting fluid flows with magnetic fields. Such phenomena are highly non-linear can often be observed both in nature and in the industry. Naturally they can be observed, for example, in stars, sun and planetary cores. In the industry, they find applications in metallurgy, materials processing and in tokamaks intended for clean energy generation through nuclear fusion. In this talk, I will present some of my research results in two important problems in MHD: a) Turbulent Hartmann duct flows at moderate magnetic Reynolds numbers, and b) Relativistic runaway electron dynamics in tokamak plasmas. The first topic is motivated both by fundamental scientific interest as well as application in liquid metal flow field measurement using Lorentz force velocimetry (LFV). The second topic concerns one of the major showstoppers in our path towards building a nuclear fusion power plant. The talk intends not to provide too many sets of results, but to rather provide a small cross-section of results that provides a big picture of my research activities.

About the speaker:

B.Tech in Mechanical engineering, Pondicherry University; M.Tech in Thermal Science and Engineering, IIT Kharagpur; Worked as an Aero & Heat Transfer Engineer for more than 4.5 yrs at GE Bangalore; PhD in Mechanical Engineering, TU Ilmenau (Ilmenau university of Technology), Germany; Continued as a postdoc at TU Ilmenau for some time. Currently working as a postdoc at Max-Planck-Institute for Plasma Physics, Garching, Germany. Research interests: Turbulence, CFD, Magnetohydrodynamics, Large scale instabilities in tokamak plasmas.

Abstract:

Proposed use of a novel server-actuated flow-boiling approach for heat removal at $B!H(BChip $B"*(B Server $B"*(B Rack $B"*(B Data Center$B!I(B levels - together with new thermal system designs incorporating a dedicated power supply approach for data centers - is shown to enable, respectively, high cooling rates for next generation chips and significant waste heat recovery (as electricity). Since large number of data centers continue to appear at increasingly large power consumption (~ 1 - 10 MWe) levels, the proposed waste heat recovery approaches have significant societal value. For dedicated power supply, one option is to utilize miniaturized Combined Cycle Power Plants (mini-CCPP) that combine mini/micro-turbines (MGTs) and Organic Rankine Cycles (ORCs). The hot air exhaust from a commercially available MGT is used as a heat-source for the ORC. It should be noted that relevant Organic Rankine Cycle (ORC) technologies are now commercially available. For data centers requiring less than 1 MWe power, there are other economically competitive power-supply options - such as use of lithium-ion battery stacks that are recharged by power generation from ORC and solar panels. This talk highlights a new approach (supported by results from new experiments) to flow boiling. The reported experiments employ a specific layering of micromeshes and diffusion bonding based inexpensive approach to micro structuring of the boiling-surface (leading to 40 - 60 % improvements in heat-flux over plane unstructured copper-surface). This approach is then augmented by our new approach that actively energizes the meshed boiling-surface. This energization is by introduction of suitable shear mode acoustic waves (of controllable amplitude and frequencies) and associated shear stresses in the micro-layers of the nucleating bubbles. For this acoustic energization, electronically controlled Piezoelectric-transducers are used - and at this time - we report additional 20-30% improvements. Even better performances are possible.

About the speaker:

Prof. Amitabh Narain (Ph. D., University of Minnesota, 1983) is a Professor in the Department of Mechanical Engineering at Michigan Technological University, USA; a Fellow of the ASME; an Associate Editor of the Journal of Heat Transfer; and Chair of ASME$B!G(Bs Heat Transfer Division K8 Committee on Theory and Fundamental Research. His current research areas deal with state-of-the-art experimental and computational techniques for phase-change (flow boiling and flow condensation) as well as single-phase flows. At system level these works relate to energy technologies such as thermal management and power generation applications - with emphasis on electronic and data center cooling.

Abstract:

Advancement of multiscale Multiphysics solution in the field of medical imaging, radiation and environmental safety invites mesoscopic mathematical tool for solving macroscopic fluid dynamics problems generally described by partial differential equations. The Lattice Boltzmann Method (LBM) suits that purpose. The idea of the LBM is to construct a simplified discrete dynamics at mesoscopic scales by implementing particles distributions on a lattice to simulate macroscopic behaviours. Literature study on several research papers suggest that LBM is a promising tool to image processing. Cerebral aneurysm is one of the most serious diseases forming part of the stroke. Aneurysm is an abnormal bulging outward of an artery. Because of certain histopathologic and hemodynamic factors, aneurysms most commonly occur in arteries that supply blood to the brain. Computed tomography angiography (CTA) plays an essential role in the diagnosis, treatment evaluation, and monitoring of cerebral aneurysms. The segmentation of giant aneurysms of the brain from CTA imaging remains a challenge. In this talk, an innovative segmentation methodology based on the combined use of the LBM and the level set method will be highlighted. Radiation safety and environmental safety can be enhanced by implementing the advanced numerical modeling (mesoscopic modeling). In this context, numerical modeling of fluid flow problem through porous media such as groundwater modeling, solute transport problem and Boltzmann Transport Equation for reactor physics simulation including uncertainty quantification will be demonstrated using LBM. Uncertainty quantification will be presented using Fuzzy set theory and Monte Carlo Simulations. Presentation will conclude by highlighting the newly developed Fuzzy LBM, which has been implemented to solve uncertainty quantification of advection diffusion reaction equation to study the migration of radionuclide through geological repository.

About the speaker:

Dr. Debabrata Datta, is a scientist in the field of radiological and nuclear science, Head, Radiological Physics & Advisory Division of Health-Safety & Environment Group, Bhabha Atomic Research Centre and Professor (Physical & Mathematical Sciences), Homi Bhabha National Institute (Deemed University), India. He has contributed in various fields of Nuclear Industry such as radiation shielding, dosimetry, criticality safety and dose database management systems. He has a good experience in handling nuclear and radiological emergency. He has more than 25 years of experience in the field of mathematical and numerical modeling, statistical data analysis, reliability and uncertainty analysis and software development. His academic excellences are: Master Degree in Nuclear Physics, Master Degree in Philosophy (Nuclear Physics) and PhD (Comp. Science). He is the associate editor of Many International Journals. He is the recipient of Eminent Scientist Award, “Millenium Plaques of Honor” from Indian Science Congress Association, in 2010. His proficiency is on software development using Machine Learning & Soft Computing technique. He is recognized internationally as one of the reviewer of IEEE and Elsevier Journals. He is an associate editor of International Journal EXPERT System (Willey Publications, Scholar one), Information Science, Environmental Modeling and Software, IJMSS and many others. Life member of many International and National Organizations. He has more than 150 publications in peer reviewed International Journals, Book Chapters, International and National Conferences to his credit. He has guided 20 M. Tech Students and 7 PhD. Students in both Engineering and Science Disciplines. His research interests are numerical modeling, statistical analysis, data mining, optimization, multi criteria decision making, algorithm development, machine learning & artificial intelligence.

Abstract:

High Heat Dissipating Two-phase Evaporative Cooling Systems for Microelectronics

About the speaker:

Prof. Oleg A Kabov graduated from the Tomsk Polytechnic State University, Russia in 1978 and received the doctoral degree from the Institute of Thermophysics, Siberian Branch of Russian Academy of Sciences in 1987. In 1999, he also received the degree of Doctor of Sciences in Physics and Mathematics (Habilitation) from the same institute. Presently, he is the Head of the Laboratory involved in activities related to Thermo-physics of Phase-Change Phenomena at the Kutateladze Institute of Thermo-physics, Novosibirsk, Siberia, Russia. For fifteen years (1997-2012), Prof. Kabov served as a scientific staff of the University of Libre de Bruxelles and managed the 'Two-Phase Systems Group' of the Microgravity Research Center at the university. He participated in a range of sophisticated experiments related to interfacial phenomena and phase-change, on board sounding rockets, on microgravity parabolic flight campaigns and on the International Space Station. Prof. Kabov has over 200 publications to his credit in refereed international journals and has 15 patents. He is also the Editor-in-Chief of the Journal 'Interfacial Phenomena and Heat Transfer'.

Abstract:

Nanomechanical sensors have demonstrated their tremendous potential in miniaturizing Mass Spectrometry which has applications in the area of biosensing and characterization. This has been made possible due to extreme miniaturization resulting in exquisite sensitivity (mass sensitivity of the order of 10-24g in controlled environment) and universal sensing surface. Among the various nanomechanical sensing techniques, nanophotonic optomechanical sensing technology (NOMS) is the most promising technique due to its exquisite displacement sensitivity. In this regard, my talk would initially focus on my recent research in the area of NOMS sensors and their integration with Gas Chromatography system, wherein I demonstrated exquisite concentration and mass sensitivity using the NOMS sensors while preserving its universality while sensing a mixture of analytes. The second topic I would be focussing on is my research findings on the effect of pressure damping on the mass sensitivity wherein I have demonstrated that as the ambient pressure increases, the mass sensitivity improves and that mass sensitivity is independent of the quality factor of the resonator. This is contrary to the conventional knowledge and helps in taking a major step towards portability. Finally I would be describing my efforts to improve the sensitivity and adsorption capacities of the mechanical resonator by reducing its mass and increasing the surface area using a simple porous etch procedure. Following the discussion of my current research, I shall expand upon my future research plans towards developing novel sensor architecture involving microchannel embedded nanomechanical resonator, liquid chromatographic column on a chip and nanophotonic cavity for liquid phase biosensing as it is the most relevant medium for biosensing. The overall goal of my research is to develop a sensing platform suitable for holistic sensing and characterization of biomolecules. Such a platform has applications in the area of data driven diagnostics and the emerging field of metabolomics based Precision Medicine.

About the speaker:

Dr. Anandram Venkatasubramanian graduated with his PhD in Mechanical Engineering from Georgia Institute of Technology. His dissertation thesis was in the area of study of molecular sieve materials such as metal organic frameworks and metal oxide nanotubes for carbon capture applications and their integration with piezoresistive microcantilever sensors for gas detection applications. His postdoctoral research concentrates on development of nanophotonic optomechanical gas sensors for biosensing applications wherein he has developed mass sensors with sensitivity upto 10-20 g and integrated them with concentration sensors with sensitivity up to few ppbs. In this seminar, he would be talking to us about his current research as well as his future research plans towards developing a portable universal sensing platform for biosensing applications.

Abstract:

Soft materials are very popular in everyday use because of ease in processing. Polymers are processed to different complex shapes from the molten state. Polymer melts display rich viscoelastic behavior in the typical length and time scales. The processing of polymer melts become difficult with increase in molecular weight (Mw) because of increase in viscosity. The long polymer chains in a melt have to move in a specific way due to the topological constraints called "entanglements" imposed by neighbouring chains. This happens because of the fact that the in a polymeric systems each monomers are connected to their neighbouring monomers and can not crossover each other. Increase in number of entanglements with increase in Mw leads to increase in viscosity. The physics of polymer melts is one of the most exciting and challenging topics of modern soft matter science. In this context, it is very interesting to study the rheological behavior of high molecular weight polymer melts (usually dominated by large number of entanglements present) in the absence of any (or large number of) entanglements. I shall present complementary experimental and simulation approaches to study the development of entanglements in a fully disentangled melt of collapsed polymer chains and changes in viscosity, moduli and glass-transition temperature during the process.

About the speaker:

Dr. Singh is currently working as a postdoctoral researcher in Prof. Kurt Kremer’s group at the Max Planck Institute for Polymer Research, Mainz. His current research work involves studying rheology of nonequilibrium polymer melts. He has done PhD under Prof. Nicholas D. Spencer at the Department of Materials, ETH Zurich, Switzerland. Prof. Martin Kroger in the Polymer Physics group in the Department of Materials, ETH Zurich was his co-supervisor. Dr. Singh defended his PhD thesis "Simulation and Experimental studies of Polymer Brushes under Shear” in Jan 2016. His PhD work involved colloidal probe-based AFM experiments and molecular dynamics simulation studies on surface grafted polymer brushes and gels in a solvent under shear. He finished his Master of Engineering (ME) degree from the Materials Engineering Department of Indian Institute of Science, Bangalore in 2011. He studied for a Bachelor of Engineering (BE) at Mechanical Engineering Department of Indian Institute of Engineering, Science and Technology, Shibpur (formerly BE College or BESU Shibpur), West Bengal, India and graduated in 2009. The principal areas of his research are tribology and rheology—mostly with polymers. He has an interdisciplinary background with education in Mechanical and Materials Engineering and research experience in both computer simulations and experiments.

Abstract:

Machine learning is a type of artificial intelligence that enables a computer to learn without being explicitly programmed. A subset of machine learning known as deep learning has evolved as one of the most compelling and cutting-edge topics of research and has demonstrated quantum leaps in accuracy in the areas of image & speech recognition and therefore are gaining popularity in the areas of bio-medical, climate and earth science research. My current research applies deep learning algorithms to study the interaction between atmospheric matter and solar radiation in general circulation models (GCMs). GCMs, predict the three-dimensional aspect of climate by numerically solving the conservation equations of mass, momentum, energy, water vapor and parameterizing the physical processes in the atmosphere such as heat fluxes due to solar radiation, evaporation, precipitation etc. The parameterization of physical processes especially radioactive heat fluxes in the atmosphere is crucial for accurate simulations of climate and weather in GCMs. These parameterizations for radiative heat fluxes in GCMs are complicated, enormous and require a tremendous amount of computational time, even with the fastest super-computers. The idea is to replace these enormous and complicated parameterizations by a simple deep learning algorithm which can compute the radiative fluxes accurately in a cost-effective manner. I have developed a deep learning algorithm which is able to calculate these radiative heat fluxes with an overall accuracy of 90% - 95% and 8-10 faster than the original parameterization. This significant speed up, without compromising the accuracy in computing the radiative fluxes using deep learning acts as a platform to explore the application of artificial intelligence for problems in fluid mechanics, turbulence and atmospheric & oceanic flows.

About the speaker:

Anikesh Pal is a Distinguished Postdoctoral Associate in Computational Climate Science at Oak Ridge National Laboratory, USA. His current research focuses on the application of Artificial Intelligence to develop innovative methods to simulate problems in fluid mechanics, turbulence, geophysical flows, and climate modeling. He received his Ph.D. in Mechanical Engineering from the University of California, San Diego. During his doctoral research, he worked on the dynamics of stratified flow past a sphere using body inclusive numerical models. This research revealed novel details on the flow physics, and the internal wave field in near to intermediate wake of a sphere under the influence of stratification. Anikesh Pal completed his Master's degree from IIT Kanpur and was a former member of the CFD lab.

Abstract:

Biomechanics and Mechanobiology are modern interdisciplinary research fields of Engineering and Science wherein the mechanics of the biological world is explored. In a generalised sense, biomechanics deals with the application of principles of mechanics to understand the physiology of living systems while mechanobiology focuses on studying the influences of mechanical environment on biological processes. With the advancements of computational power, it is now possible to understand the complex biomechanical behaviours of normal and pathological human joints through numerical simulations or in silico evaluations. Consequently, this has resulted in computational biomechanics and mechanobiology as an emerging research domain. This talk covers the state-of-the-art techniques of computational biomechanics and mechanobiology, in particular, biomedical image processing, musculoskeletal modelling and finite element (FE) analysis along with their applications in bone and joint mechanics. The talk is divided into two parts. Part one of the talk encompasses how does numerical simulation help to gain an insight into the influences of implant surface texture designs on the peri-prosthetic osseointegration. Starting from a patient-specific CT scan data, the talk elaborates the process of developing an FE model of human bone and joint. Thereafter, the talk presents a numerical framework to investigate the osseointegration of the implant. Part two of the talk covers how do computational techniques help in understanding the influence of fetal movements on prenatal bone and joint development. In this part, the talk proposes a novel numerical framework, combining musculoskeletal modelling with FE analysis, to investigate the mechanical stimuli induced by fetal movements in the murine embryonic hindlimb at different stages of development.

About the speaker:

Dr Kaushik Mukherjee is a Marie Skłodowska-Curie Research Fellow in the Department of Bioengineering, Imperial College London, UK. His research is in the area of Developmental Biomechanics. In particular, he is investigating the influences of abnormal gait in the development of postnatal joint abnormalities using a mechanobiological simulation of growth and morphogenesis. Prior to this fellowship, Dr Mukherjee was a postdoctoral Research Associate at the Developmental Biomechanics Group, Imperial College London. Dr Mukherjee investigated the influence of movements on prenatal joint development using computational models. Dr Mukherjee completed his undergraduate (B.Tech) in Mechanical Engineering from West Bengal University of Technology (India) in 2010. Thereafter, he joined the Department of Mechanical Engineering, Indian Institute of Technology Kharagpur (India) as a Joint M.Tech-Ph.D. student. He completed his master's degree (M.Tech) in 2012 with a specialisation in Mechanical Systems Design and continued his doctoral research in the field of Orthopaedic Biomechanics and Implant Design. He completed his doctoral degree in June 2017. His research interests are Orthopaedic Biomechanics, Implant Design, Computational Mechanobiology and Developmental Biomechanics.

Abstract:

Ever restricting government regulation to curb fuel emission and demand of high fuel efficiency due to diminishing stock of fossil fuel are some of the vital reasons compelling automobile industries to reduce car body weight with application of newer materials or combination of materials. Therefore, advanced high strength steels (AHSS) and its tailor welded blanks are increasingly used by the automobile industries. In the fast part of the presentation, the influence of dissimilar material and non-homogenous weld zone properties on the forming behavior in Tailor Welded Blanks (TWB), potential of dual phase TWBs in complex auto body applications, mathematical framework to convert strain based forming limit diagram (FLD) to stress based FLD for failure prediction in multistep forming will be highlighted. However, finite element (FE) simulations for accurate prediction of formability of sheet metals is very crucial for industries, prior to implementation of newer auto body design for efficient utilization of materials and resources. Therefore, in the second part of the presentation the implementation of evolution of anisotropic yield function in the Marciniak-Kuckzinki (MK) model and in the FE simulation for improvement of prediction accuracy of sheet metal formability will be discussed. In the third part, the robust simulation approach for solving complex thermo-mechanical problems induced by the quenching (i.e., external water cooling), internally generated heat due to phase transformations, and heat transfers between core and surface will be demonstrated. Finally, the plan for advancing the research in sheet metal forming area along with laser welding, cladding or other thermomechanical processes involving phase transformation will be presented.

About the speaker:

Dr. Kaushik Bandyopadhyay is currently working as Research Professor in the Korea University, Seoul, South Korea. He received his PhD degree from Indian Institute of Technology, Kharagpur on Formability analysis of laser welded dual phase steel sheets for auto-body applications in 2015. Prior to his research professor position, he worked at NIT Warangal as an ad-hoc faculty. His research interests are Sheet metal forming, Constitutive modelling, Failure analysis, Laser material processing etc. In recent years, he is also working on Modelling of phase transformation kinetics in steel subjected to TempCore process. He has published 12 articles in various international journals such as International journal of solids and structure, International journal of mechanical sciences, Materials and design, Material science and engineering A, Journal of material processing and technology etc. He authored two book chapters. He has presented an invited talk in International conference on plasticity, damage, and fracture (ICPDF2018, San Juan).

Abstract:

Thermoacoustic instability has been a major concern for gas turbine combustors employed in power generation and aviation engines in the last few decades. In this talk I will discuss research aspects concerning thermoacoustic instability in gas turbine combustors which are presently of immediate relevance to the industry, and which have also been part of my previous research activities. Specifically, I will focus on flame dynamics under the influence of multi-dimensional acoustic fields and the nonlinear and stochastic dynamics of thermoacoustic instability.

About the speaker:

Dr. Saurabh is a Research Scientist at the TU Berlin, Germany. He has a PhD in Engineering Physics from the TU Berlin (2017). He graduated from the Dept. of Aerospace Eng., IIT Madras with a dual degree in 2010. His research experience spans topics concerning combustion noise, thermoacoustic instabilities, premixed flame dynamics, and passive acoustic dampers.

Abstract:

Electrocaloric effect in ferroelectric materials is observed due to the domain switching behaviour at micro-scale. Under the applied electric field, domains will orient along the direction of the applied filed. This reduces the randomness or uncertainty in the orientation of the unit cell. If the applied field is rapid enough to be considered as an isentropic process, the decrease in orientation or configurational entropy is compensated with the increase in the energetic entropy. This leads to the increase in temperature. Similarly, rapid removal of electrical field decreases the energetic entropy and hence the temperature of the ferroelectric material. This change in temperature of the material due to change in electric field is known as electrocaloric effect (ECE) and the change in temperature during the process is known as adiabatic temperature change. Characterisation study on ferroelectric materials for this property becomes important as this material can be used as solid state refrigerants for this particular behaviour. Direct Measurement of the adiabatic temperature change has some practical difficulties. Hence, using Maxwell relation, an indirect experimental method is used to calculate the temperature change. In this seminar, an indirect method commonly followed to measure the electrocaloric effect will be introduced and its result which leads to the physically non-viable conclusion of negative adiabatic temperature change will be addressed. Following that, an alternate method will be proposed which can overcome this issue.

About the speaker:

After his B.E in Mechanical Engineering from Dr. Sivanthi Aditanar college of Engineering, Dr. Maniprakash Subramanian went to IITM to do his M.Tech in the department of Applied Mechanics (Solid Mechanics), IITM. Later, he joined in TATA Motors Ltd as a Development Manager. After working there for two years, he went to the Institute of Mechanics, TU Dortmund, Germany to pursue his PhD in the phenomenological modelling of ferroelectric materials. Later, he came back to IITM as an Institute postdoc in the Department of Applied Mechanics and worked there for two years. Currently, he is working as an Assistant Professor at the school of Mechanical Engineering, SASTRA University, Thanjavur

Abstract:

An accurate characterisation of transportation and industrial noise is vital for the control of environmental noise pollution, a known public health issue, and also for defence applications. Similarly, diagnosing material damage is critical for air vehicle safety, assessing damage in bones and organs as well as civil infrastructure. Diagnostic time-reversal (TR) imaging, an inverse method, can profoundly improve the resolution of these singularities in fluid and solid media by focusing waves along the same trajectory as that taken during emission. In this talk, I will present an overview of my work on the application of TR imaging for localising aeroacoustic sources based on numerical (finite-difference based) solution of linearized Euler equations (LEE). A mapping of aeroacoustic sources promises to yield a better insight in the understanding of the pertinent flow-induced noise mechanisms. First, using test-cases of idealized source located in mean flow, advancements in implementing TR simulation over a two-dimensional domain are presented. This includes development of novel damping techniques which improves the capacity of TR to unambiguously localize sources and produce super-resolution. Following this, the TR algorithms are implemented using experimental data acquired in a wind-tunnel to three canonical problems, namely, low Mach number flow over a cylinder, and an airfoil as well as rod-airfoil interaction. While the TR method is shown to characterize the dipole nature as well as yield an accurate localization of the Aeolian tone source, it suffers from the well-known limitation of minimum half-wavelength resolution. To overcome this, a multi-stage point-time-reversal sponge-layer (PTRSL) technique is proposed which is shown to produce a point-like enhanced super-resolution of the Aeolian tone source, though it does not improve the localization accuracy. Next, the test-case of a rod-airfoil interaction noise is considered wherein the effect of self-scattering (by modelling the airfoil) on source location and resolution is analysed. Finally, the TR method is used to localize noise sources generated by flow over an airfoil whereby it is shown that without modelling self-scattering during simulations, the dipole location was found to be in the trailing-edge (TE) wake. When the self-scattering was taken into account, the scattered source exhibited a cardioid directivity, however, large side-lobes located in the wake, presents difficulty in readily identifying its true location, particularly, at low- and high-frequency range. To remove this ambiguity, an iterative PTRSL damping technique is proposed which is centred at an optimal location (along the chord) obtained through iterations. The implementation of iterative PTRSL damping yields the scattered source location between the mid-chord and TE region, thereby improving the localization accuracy, particularly in the low-frequency broadband and high-frequency secondary tones. Towards end of my talk, I will touch upon my research vision comprising of application of array processing techniques to localize aeroacoustic noise sources generated by more complex test-cases as well as some research ideas in duct/muffler acoustics.

About the speaker:

AKHILESH MIMANI is an Assistant Professor at School of Engineering and Applied Science, Ahmedabad University since June 2018. Akhilesh received his PhD (2012) in Mechanical Engineering from the Indian Institute of Science, Bangalore. He has completed research associate positions at The University of Adelaide (2016), University of New South Wales (UNSW) Sydney (2017) and University of Technology Sydney (2018) before joining Ahmedabad University. Other than Time-Reversal and Beamforming array processing techniques, his research interests are in the field of Muffler and Duct acoustics, experimental and computational aeroacoustics and application of finite element analysis to acoustic wave propagation problems. Akhilesh’s work has been published in reputed journals and conference proceedings, and has an upcoming Springer monograph on automotive muffler design. He has received funding from the (Australian) industry, in addition to a few travel grants. Additional details are attached.

Abstract:

Computational Fluid Dynamics (CFD) is concerned with the numerical solution of the equations governing fluid flow, heat transfer and multi-species transport in fundamental and industrial problems. In the past 50 years, the subject of CFD has grown significantly in several directions, aided primarily by the growth in computing power. Today, a large variety of problems are being addressed with billions (or hundred of millions) of discrete points, which has grown from a few thousand used in the 1970s. This has provided unprecedented resolution, speed and data visualization capabilities which were not available five decades earlier. Thus the limits of fidelity in the simulations have been significantly extended. Direct and Large-eddy simulations of turbulent flows, though computationally more expensive are now possible at high resolution. Petascale and Exascale computers will further pave the way to perform well-resolved single and multiphase flow simulations using both CPU and GPU parallel processors. However, accurate simulations of fluid flows (except for a few problems) are still difficult because of several complexities, including: a) high Reynolds number; b)chemical reactions; multiphase flows and associated flow regime identification, etc. In addition, knowledge of accurate boundary and initial conditions for industrial flows remains uncertain. Thus, CFD cannot be considered to be an exact predictive tool for the near term, but serves as a good estimation technique. These constraints limit the growth of CFD to be an exact science. I will present examples of both aspects from work performed in my group.

About the speaker:

Prof. Pratap Vanka is a Research Professor and Professor Emeritus in the Department of Mechanical Science and Engineering at the University of Illinois at Urbana-Champaign, USA. He graduated from Banaras Hindu University with a Bsc(Engg) (Hons) in 1968, and an M. Tech. from IIT-K in 1970. He obtained his Ph.D with the legendary Prof. D. B. Spalding at Imperial College in 1975 after working at Tata Consulting Engineers for two years. From 1979-1989 he worked at Argonne National Laboratory, prior to moving to University of Illinois at Urbana-Champaign. He is currently Professor Emeritus, but continues to teach and supervise graduate students. He is a Life Fellow of ASME and Fellow of APS. He has won several teaching and research awards, and has published more than 160 technical journal/conference papers. He is currently visiting IIT-H as a VAJRA professor from MHRD.

Abstract:

The FRacture ANalysis Code 3D (FRANC3D) program is designed to simulate 3D crack growth in engineering structures where the component geometry, local loading conditions, and the evolutionary crack geometry can be arbitrarily complex. It is designed to be used as a companion to general purpose Finite Element (FE) solvers. FRANC3D · Allows the use of existing finite element models · Provides more accurate forecast of component life expectancies · Precision and depth can be added to the results by incorporating · Fretting nucleation module can be used to compute the number of load cycles to crack nucleation and initial crack location for fretting applications · 3-D fracture modeling into engineering analysis · Reduce cost; Fully automatic crack growth process · Provides a more efficient method for designing engineering components In this webinar, we will provide an overview of the Franc3D Capabilities, including · Crack Growth Prediction, Path of the rack growth · SIF Computation for all modes · Computation of SIF by using M-Integral

About the speaker:

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Abstract:

The present study focuses on experimental investigation of spray from an airblast injector in the presence of crossflow; and attempts to gain insight that can further lead to the development of fuel injection system for gas turbine combustors. Spray in crossflow is a phenomenon of recent interest and appears to have better potential than the traditional jet in crossflow injection. The first part of this study focusses on jet in crossflow. Jet trajectory and effect of nozzle geometry on jet breakup are investigated. Proper Orthogonal Decomposition analysis is also used to gain further understanding of the breakup process. Surface waves on liquid jets are characterized and a theoretical framework is developed to predict the wavelength of these waves. In the second part of this investigation, structure, trajectory and droplet size distribution for spray in crossflow are studied. Effect of operating parameters on spray structure is studied in detail. Different spray regimes are observed, and a regime map is proposed based on detailed characterization of spray behavior. A brief discussion is also included about the recent research on Hydrogen explosions in vented enclosures. A new phenomenological model based on spherical flame propagation is developed which is found to be in good agreement with the experimental data.

About the speaker:

Anubhav completed his B.Tech. in Mechanical Engineering from NIT, Jalandhar in 2007. His major project was on Flame-jet impingement on flat plate. During B. Tech., he did internship at CFD Laboratory, IIT Kanpur. He also underwent industrial training at Tata Motors, Jamshedpur, and Diesel Locomotive Works, Varanasi. After completing B. Tech., he got employed in Ashok Leyland, where he worked as a Deputy Manager in engine assembly and vehicle assembly plant at Hosur and Chennai. He left Ashok Leyland in 2009 to join IISc, to pursue PhD in Mechanical Engineering. His PhD research was focused on designing novel injection strategies for compact combustors. After completing PhD, in 2015, he got recruited in GE-Aviation as a Lead Engineer. There he worked on design of next-generation combustors, and issues related to thermo-acoustic instability in gas turbine engines. He left GE to join University of Warwick, UK for a post-doctoral position in 2017, where his research is focused on vented explosions of Hydrogen and methods to mitigate them.

Abstract:

Classical and quantum systems driven by a high frequency field are generally called periodically driven systems. The dynamics of a single particle driven by time-periodic forces can be solved for using various well established techniques like Hamiltonian averaging theory. However, a study of the statistical mechanics of a collection of particles in such systems requires obtaining a solution for the particle distribution function, instead of the trajectories of each single particle. If the system is collisionless, the distribution function is given as a solution of the Liouville or Vlasov equation, and in the presence of collisions, the Fokker-Planck equation is generally used. Interestingly, he solutions of the Vlasov equation, for systems with external periodic driving, are aperiodic for most initial conditions [Physics of Plasmas 25, 042302 (2018)]. However, solutions of the Fokker- Planck equation for such systems seem to be periodic asymptotically for most initial conditions [Physics of Plasmas 17,054501 (2010)]. This drastic change in the nature of solutions as we go from the collisionless to collisional situation is currently not well understood, but can have important implications for our understanding of RF heating commonly observed in such systems (eg. Paul traps). Another setting in which these periodically driven systems are of immense importance is a particle moving within a dynamical billiard with one of the boundaries connected to a spring. This is useful not only in understanding mathematical properties of dynamical systems in general, but also in modeling of plasma interaction with high frequency RF fields (eg. Fermi acceleration). An important question here is whether the partial energies of the various components of the system equilibrate. Altering the traditional ergodic assumption, we have recently shown that nonergodicity in one of the subsystems leads to equilibration of energies of the whole system [PNAS USA 114, E10514 (2017)].

About the speaker:

Dr. Kushal Shah is an Associate Professor in the EECS Department, IISER Bhopal. He earned his BTech and PhD from IIT Madras in 2005 and 2009, respectively. He was a Post-doc at Weizmann Institute of Science, Israel from 2009-10. He served as a faculty at JNU (N. Delhi) from 2010-12, and then at IIT Delhi from 2012-17. He moved to IISER Bhopal in 2017 due to rising pollution in Delhi.

Abstract:

Stochastic computational fluid dynamics (CFD) are elegant approaches for solving continuum turbulent flow problems. Their great attraction is that they provide inherently closed formulations for non-linear, small scale processes such as chemical reactions and discrete particle dynamics. Although stochastic approaches have traditionally been considered to be computationally expensive, it is possible to alleviate this by complementing them with low-dimensional manifold and dynamic binning methods. This seminar will present recent stochastic CFD research from the University of Sydney with applications in combustion, soot and nanoscale materials synthesis, and two-phase flows.

About the speaker:

Associate Professor Matthew Cleary is an academic in the School of Aerospace, Mechanical and Mechatronic Engineering (AMME) at the University of Sydney where he leads the modelling research conducted by the Clean Combustion Research Group, teaches undergraduate and postgraduate courses in thermofluids and is the Director of Research. He has bachelors degrees in both Mechanical Engineering and Naval Architecture and obtained his PhD in 2005 from the University of Sydney. Cleary has held previous positions at Imperial College London, the University of Queensland and a visiting position at Princeton University. Cleary is best known for his work on developing the multiple mapping conditioning / large eddy simulation (MMC-LES) model for turbulent reacting flows, which has revolutionised the use of stochastic particle methods through sparse (and therefore very low cost) Monte Carlo solutions. Cleary instigated and continues to lead a major opensource combustion code development collaboration, known as mmcFoam, between researchers at eight universities in Australia, India, Germany and China.

Abstract:

The seminar will focus on explaining the detection, sizing, and localization of damages such as closed transverse crack, delamination, and disbond, present in thin plates, using nonlinear response of Lamb waves. The experiments and numerical simulations carried out in this regard will be discussed during the seminar. The damages mentioned above are also called as breathing damages as they breathe, i.e., open and close as the wave passes across them. The contact nonlinearity prevails in breathing damages and typically produces higher harmonics in the Lamb wave response at a relatively lower excitation frequency. The seminar will also cover the issues that need to be addressed in order to use this method to assess the health of complicated structures in real-time.

About the speaker:

Dr. Nitesh P. Yelve is presently ‘Dean (PG Studies)’ of Fr. C. Rodrigues Institute of Technology, Vashi, Navi Mumbai and also holding the post ‘Associate Professor’ in the Department of Mechanical Engineering of the same Institute. He received his M.Tech. degree in Mechanical Engineering from VJTI, Mumbai and received his Ph.D. from the Department of Aerospace Engineering of IIT Bombay. He also pursued the Postdoctoral Fellowship at City University of Hong Kong in 2017. He has more than 16 years of teaching and research experience. The areas of his research interest are structural health monitoring using ultrasonic guided waves and vibration methods, active vibration control, structural dynamics, and composite materials. He has guided many undergraduate and post-graduate students for their projects and currently guiding a Ph.D. student. He has presented 46 papers in National and International Conferences in India and abroad, published 23 papers in International Journals, and also filed a patent. He is Member of Aeronautical Society of India, Astronautical Society of India, ASME, IEEE, Condition Monitoring Society of India, Institute of Smart Structures and Systems, and ISTE. He is also holding the post of Executive Committee Member in Mumbai Branch of the Aeronautical Society of India.

Abstract:

Understanding the fundamental mechanisms of magnetohydrodynamic multiphase and multiscale transport phenomena is of vital importance in the design of advanced scientific and technological applications, namely, continuous casting flow control mold, flow augmentation in micropumps, magnetophoresis, separation of biological and chemical moieties, magnetohydrodynamic flow control, smart sensors, micro/nano‐electromechanical devices/sensors, to name a few. Towards achieving this goal, the present work attempts to study the effect of superimposed magnetic field in multiphase and multiscale transport characteristics through the development of analytical and computational models, which are perfected with experimental investigations and exact analytical solutions. For a multiphase system concerning binary alloy solidification, the linear stability analysis (LSA) results indicate that the magnetohydrodynamic effect imparts a stabilizing influence during both stationary and oscillatory convections. In comparison to that of stationary convective mode, the oscillatory mode appears to be critically susceptible at higher values of the Stefan number and concentration ratio. Increasing magnetic strength shows reduction in the wavenumber and in the number of rolls formed in the mushy layer. In multiscale paradigm, the combined electroosmotic and pressure‐driven transport through narrow confinements have been firstly analyzed with an effect of spatially varying non–uniform magnetic field. It has been found that a confluence of the steric interactions with the degree of wall charging may result in heat transfer enhancement, and overall reduction in entropy generation of the system under appropriate conditions. It is also inferred that incorporating non–uniformity in distribution of the applied magnetic field translates the system to be dominated by the heat transfer irreversibility. A semi‐analytical investigation has been undertaken considering implications of magnetohydrodynamic forces and interfacial slip on the heat transfer characteristics of streaming potential mediated flow in narrow fluidic confinements. An augmentation in the streaming potential field as attributable to the wall slip activated enhanced electromagnetohydrodynamic transport of the ionic species within the EDL has been found. Furthermore, the implications of Stern layer conductivity and magnetohydrodynamic influence on system irreversibility have been shown through entropy generation analysis.

About the speaker:

Sandip Sarkar graduated in Mechanical Engineering from IIEST Shibpur, India. Thereafter, he did his M.Tech. in Mechanical Engineering from IITK in May 2008. In early 2017, he completed his PhD in Mechanical Engineering with Fluids and Thermal Science specialization from the Indian Institute of Science, Bangalore, India. His thesis work primarily focused on LSA, micro-scale flow, heat transfer, and entropy generation analysis. He has published 31 research papers in various international journasl of repute and has presented 7 papers at various international conferences. He has overall 8 years of industrial research experience in the R&D Division of Tata Steel.

Abstract:

In the last few decades, the use of carbon fibre reinforced polymer composites as structural materials has dramatically increased in aviation, transportation, construction and many other related applications. This is due to their remarkable structural and functional advantage over traditional metals such as low weight, high strength to stiffness ratio, customisable elastic properties, better fatigue endurance etc. Structures are manufactured by stacking a number plies with different fibre orientations on top of each other to form a laminate, followed by consolidation and thermal cure in an autoclave. Despite achieving superior in-plane properties, upon mechanical loading, composites typically tend to fail along the weaker inter-ply boundaries, also known as ‘delamination’. Additional failure mechanisms include intra-ply matrix cracking, fibre compressive failure or ‘kinking’ etc. These mechanisms seldom occur in isolation but interact among themselves during failure leading to a complex overall load carrying behaviour. This invalidates simple safety-factor based design guidelines and necessitates application of three dimensional progressive failure criteria implemented in finite element models for accurate prediction of structural load carrying capacity. This talk will explore failure emanating from a very common manufacturing induced defect in laminates, known as ‘wrinkle’ or out-of-plane fibre waviness, both from an experimental and numerical perspective. Several advanced three dimensional progressive damage modelling methods in composites, developed within in the University of Bristol, will be discussed and their ability to accurately reproduce the complex progressive and interactive nature of failure under various loading cases will be demonstrated.

About the speaker:

Dr Supratik Mukhopadhyay obtained B.E in Production Engineering from Jadavpur University, Kolkata in 2009. The same year, he was also awarded the University gold medal for standing first in order of merit in the department. Following this, he continued with an M.Tech programme in the specialization of Manufacturing Science and Engineering in the Mechanical Engineering Department of Indian Institute of Technology, Kharagpur, where he obtained the Institute silver medal for academic excellence. Subsequently, he went to UK on a Dorothy Hodgkin Postgraduate Scholarship to pursue a PhD in Aerospace Engineering in the University of Bristol on a Rolls-Royce sponsored project. His research was on experimental and computational investigation of failure from manufacturing induced defects in composite laminates used for aircraft engine applications under static and cyclic loads. As part of that, he developed and implemented several novel three dimensional progressive failure models for intra and inter-laminar damage as user defined material and element formulations for commercial finite element solvers in the explicit-dynamic framework. He also gained extensive experience in code development for large scale models running in cluster computing system. The models very accurately reproduced experimental observations for detailed laminate failure under various loading conditions. The outcome of this PhD resulted in several publications and won the prestigious ‘Kenneth-Harris James Prize’ by IMechE (Institute of Mechanical Engineers), UK and also the vice-chancellors commendation for one among the ten best outgoing PhDs in the academic year 2015-16. Since October 2015, he is a Post-Doctoral Research Associate in the R-R UTC (Rolls-Royce University Technology Centre), based in the same department, and working on several Rolls-Royce funded projects.

Abstract:

Microfuel cells are high potential alternative power sources compared to conventional batteries. In microfuel cell due to co-laminar flow, the convective mixing between anolyte and catholyte is avoided thus leading to a well-defined liquid-liquid interface. The lack of a physical membrane resolves many issues related to membrane conditioning and improves cell efficiency. Another important factor which can affect the efficiency of cell is its electrode architecture. Different designs such as flow-over design with planar electrodes and flow-through design with three-dimensional porous electrodes is possible. The impact of flow and electrode architecture on cell performance and fuel utilization will be discussed along with the efficacy of flow-through electrodes as compared to the established flow-over format.

About the speaker:

http://www.iitk.ac.in/me/data/bhuvana-t-CV.pdf

Abstract:

A robot can position and orient its end-effector or a tool arbitrarily in three-dimensional space if it has six independent actuators. However, from early days, robots with more than six actuated joints have been built and in biological systems more than the required number of actuated joints is very common. In such redundant systems, for a given position and orientation of the end-effector there exists infinitely many possible actuated joint variables and a fundamental problem is to obtain or choose one such solution set so that the desired position and orientation of the end-effector can be obtained. In this talk, various approaches to resolve redundancy, starting from a work done more than 30 years back to some recent results developed by the speaker and his students, will be presented. Examples of resolution of redundancy in serial and parallel robots, in a human arm and in an actuated endoscopic tool will be presented.

About the speaker:

Ashitava Ghosal is a Professor in Mechanical Engineering Department and the Centre for Product Design and Manufacturing at IISc, Bangalore. He obtained a B. Tech from the Indian Institute of Technology, Kanpur and a PhD from Stanford University, California. His broad research areas are kinematics, dynamics, control and design of robots and other computer controlled mechanical systems. He has authored a text book entitled “Robotics: Fundamental Concepts and Analysis” by Oxford University Press. He has 3 patents, around 70 archival journal papers and 75 papers in national and international conferences. He has guided 13 PhDs, 15 MSc (Engg) and more than 35 ME students. He is currently serving as an elected member of the executive committee of the International Federation for the Promotion of Mechanism and Machine Science (IFToMM) for the term 2016-19.

Abstract:

Energy is primarily transported by quasiparticle (QP) vibrations – collective excitation of electrons, electron spin (also known as magnons or spin waves) and atoms (also known as phonon). Recent advances in theoretical simulations and experimental resources have now made it possible to directly map these QPs at the atomic scale, providing opportunities to understand the underlying mechanisms governing the energy flow. In a perfect harmonic crystal, energy flow is infinite; however, in real materials, QPs are scattered by defects, impurities, boundaries, and via coupling to other QPs, thus impeding the flow. The QP vibrations and coupling also govern the phase transitions and the thermodynamic properties, i.e., entropy, internal energy, and free energy. This talk will discuss the underlying physics of the QP coupling, its impact on the energy transport in thermoelectric Mo3Sb7-xTex [1], multiferroic CuCrO2 [2], and ferroelectric (FE) phase transition in magnetoelectric YMnO3 [3]. We have performed comprehensive inelastic neutron scattering (INS) and inelastic x-ray scattering (IXS) measurements combined with first-principles density functional theory simulations. Our combined experimental and theoretical study quantifies the strength of electron-phonon coupling in Mo3Sb7-xTex, and spin-phonon coupling in CuCrO2, which dominates the scattering rates and govern the energy flow. Moreover, in YMnO3, our results directly reveal phonon instability driving the paraelectric to FE phase transition -- providing the first direct evidence of geometric improper ferroelectricity, and its coupling with the polar phonon inducing the permanent polarization below the FE phase transition. 1. D. Bansal et al. “Electron-phonon coupling and thermal transport in the thermoelectric compound Mo3Sb7-xTex.” Physical Review B, Vol. 92, 214301, 2015. 2. D. Bansal et al. “Lattice dynamics and thermal transport in multiferroic CuCrO2.” Physical Review B, Vol. 95, 054306, 2017. 3. D. Bansal et al. “Momentum-resolved observations of the phonon instability driving geometric improper ferroelectricity in yttrium manganite.” Nature Communications, Vol. 9, Article No. 15, 2018.

About the speaker:

Dr. Dipanshu Bansal is a postdoctoral researcher in the Mechanical Engineering and Materials Science department at Duke University. His current research is focused on the study of "Quasi-particle coupling in the transport of heat, charge and spin" using first-principles electronic, lattice, and spin dynamics simulations along with experimental neutron and x-ray scattering. Dr. Bansal obtained his bachelor degree from IIT Kanpur in 2010, M.S. and Ph.D. from SUNY at Buffalo in 2012 and 2015, respectively. His Ph.D. work involved the study of anharmonic behavior in thermoelectrics, superconductors, and negative thermal expansion materials. Dr. Bansal joined Oak Ridge National Laboratory in June 2015 as a postdoc and performed neutron and x-ray scattering experiments to investigate quasi-particle coupling in thermoelectrics and multiferroics.

Abstract:

In the last four decades several missions were planned and executed successfully to explore the planet Mars. An in depth knowledge of the Martian terrain was obtained with the help of spacecrafts landing on its surface and performing various scientific tasks. Though the planet has thin atmosphere compared to earth, atmospheric entry, descent and landing is highly challenging. Specially, the atmospheric entry, though lasts for only minutes, is a very crucial stage of the mission, as the spacecraft is subjected to severe aerodynamic forces and heating. The spacecraft enters the planet at speeds in excess of 6 km/s, at which aerodynamic heating is large enough to disintegrate the spacecraft, if not provided with proper thermal protection system (TPS). The design and development of TPS depends on the reliable data on aerodynamic heating. Although the computational fluid dynamic codes are fast emerging as a means to compute such data, experimentally measuring the data in ground test facilities is still a preferred means of obtaining the design data, which will also be useful for validating the numerical codes. The TPS commonly used for planetary entry spacecrafts are ablation cooling systems. Though they have been used successfully in all Mars missions, they are expensive and have certain drawbacks. This drove us to explore the feasibility of using alternate TPS. In this presentation, the experiments carried out in hypersonic test facilities for investigating mass transfer cooling technique, film and transpiration cooling techniques, shall be discussed in detail.

About the speaker:

Dr. Mohammed Ibrahim. S, Dept. of Aerospace Engineering, IITK

Abstract:

Automobile and aerospace industries are facing problems more and more on reducing the weight and manufacturing cost of a structure, but guaranteeing an equal level of comfort with satisfactory structural performance of components. To overcome these contradictory requirements traditional designs and materials must be revised. Therefore, this work presents a methodology to design, manufacture and characterise the properties of novel contoured-core sandwich structures to obtain strong, stiff and lightweight structures including air ventilation to reduce the danger of deterioration and humidity retraction. Two different contoured profiles, named flat-roof and spherical-roof contoured-cores, were designed to investigate structural response under quasi-static and dynamic loading conditions. Flat-roof and spherical-roof structures were made from a glass fibre reinforced plastic (GFRP) and a carbon fibre reinforced plastic (CFRP). The composite contoured cores were fabricated using a hot press moulding technique and then bonded to skins based on the same material, to produce a range of lightweight sandwich structures. Testing was initially focused on establishing the influence of the number of unit cells, thickness of the cell wall, width of the cell and the core filled with foam on their mechanical behaviour under quasi-static loading. The compression strength and modulus were shown to be dependent on the number of unit cells and the cell wall thickness. It has also been shown that the specific energy absorption capacity of the panel increases with increasing the cell wall thickness, with the spherical-roof cores outperforming their flat-roof counterparts. Moreover, the foam filling on the composite contoured-core systems improved the strength as well as specific energy-absorbing characteristics of the structures. Low velocity impact loading was subsequently performed on the sandwich structures and showed that the values of energy absorption were slightly higher than the tests conducted at quasi-static loading, as a result of the rate-sensitive effects on the damage resistance of the composite material. In addition, blast tests were undertaken to subject the core materials to a much higher strain-rate. Extensive crushing of the contoured cores was observed, suggesting that these structures are capable of absorbing a significant amount of energy under the extreme loading condition. Finally, the results of these tests were compared with previously-published data on a range of similar core structures. The energy absorbing characteristics of the current spherical-roof systems are shown to be superior to other core structures, such as aluminium and composite egg-box structures..

About the speaker:

Dr. Amit Haldar from the Shenzhen Fiber Novel Material, China

Abstract:

Our conventional understanding is that Bernoulli’s equation is only applicable to irrotational flows. In the first part of this talk we will generalise unsteady Bernoulli’s equation to flows with piecewise constant background vorticity. This generalisation is crucial for understanding the dynamics of a density interface sandwiched in a shear layer (i.e. a "sheared" density interface), as is the situation in many environmental shear flows, e.g. the lake thermocline, the air-sea interface, the ocean pycnocline. Using a numerical technique known as vortex method, we will show how the evolution of a single sheared density interface (as well as multiple interfaces) can be effectively modeled. Furthermore, it will be shown that vortex method accurately captures highly nonlinear features like the breaking of surface gravity waves, Holmboe waves and capillary-gravity waves. In the next half of the talk, we will focus on wave triads, especially Bragg resonance, which is basically the interaction between interfacial waves and bottom topography. It will be shown that the base flow has a non-trivial effect on the triad resonant condition.

About the speaker:

Anirban Guha is an Assistant Professor in the Department of Mechanical Engineering at IIT Kanpur. Before taking up this position, he was a postdoctoral fellow in the Department of Atmospheric and Oceanic Sciences at UCLA. Dr. Guha completed his Ph.D. from The University of British Columbia in 2013. He was a recipient of the 2013 David Crighton fellowship from the Department of Applied Mathematics and Theoretical Physics (DAMTP), University of Cambridge and several awards and scholarships from UBC, including the Earl R. Peterson memorial scholarship, Faculty of applied science graduate award and the Four-year fellowship. Dr. Guha is primarily interested in understanding hydrodynamic instabilities, waves and vortices occurring in environmental flows.

Abstract:

Cracks follow intriguing trajectories that seem to hide a mysterious secret. Ancient Chinese civilization interpreted the tortuous path of cracks in turtle shells as an oracle to foresee the future. Nowadays, fractography, the study of fracture surfaces, is a broadly used engineering technique that aims at tracing back the history of a failure and determining its root causes. For 30 years, the study of fracture patterns has taken a new turn: could we learn from the morphology of cracks the fundamental laws of fracture? During this presentation, I will present some remarkable advances in the understanding of fracture patterns and I will explain how they challenge the current theory of fracture and, in fine, contribute to improve it. I will first discuss how to decipher triangular patterns observed on fracture surfaces of polymeric solids and why it contributed to understand on how tensile cracks behave in presence of shear. Then, I will focus on crack roughness that is the fingerprint of the interaction of cracks with the microstructure of materials. I will present how their statistical properties reveal basic crack growth mechanisms, leading us to revisit, and even reconcile, the concepts of ductile and brittle failure. Last but not least, I will discuss some implications for engineering sciences. Even though the analysis of fracture patterns still does not help to foresee the future, it can now be used to trace back the history of the failure and characterize material properties with unprecedented accuracy and reliability.

About the speaker:

Dr. Laurent Ponson is CNRS faculty at Institute d’Alembert for mechanics of Sorbonne University where is also head of the Solid and Structural Mechanics group that consists of about 20 faculties. After graduating from the Engineering school Centrale-Paris in 2003, he earned a doctorate in Physics at Ecole Polytechnique in 2006 for his work on the statistical properties of fracture surfaces for which he received the thesis prize Daniel Guinier from the French Society of Physics. He then worked for three years at the California Institute of Technology as a post-doctoral scholar before joining Sorbonne University in 2011. His research interest lies in the fracture behavior of heterogeneous materials that he investigates by the combination of theoretical, numerical and experimental studies.

Abstract:

Motility is an essential characteristic of many biological cells. For the unicellular organisms, such as bacteria, it is crucial for their survival. For the multicellular organisms it is required for some of the physiological functions, such as protection against pathogens by the immune cells, during development and disease. In this talk I am going to present some examples of the cellular motions and the mechanics behind them. *Clamydomonas, *an aquatic unicellular microorganism uses two flagellae to move from one place to another. Its small size results in negligible inertial forces and its motion is described using Stokes flow. Recently, our immune cells have also been shown to move in fluid by similar mechanism as deployed by *Clamydomonas. *This motion which does not require any support from solid substrate for the cellular motion has been labelled “amoeboid swimming”. The influence of the hydrodynamic as well as adhesive interaction of these motile cells with substrates on their motion will be presented. I will also highlight the fundamental differences between these interactions of amoeboid swimmers and flagellated swimmers with substrates. Another example of cell motion is collective cell migration which is essential during animal development and in conditions such as wound healing. I will show an example of the regulation of the collective cell migration in the epithelial tissues during development. The motion of cells in tissues adds another layer of complexity which arises from its genetic regulation. I will show how the subcellular proteins affect the mechanical properties of the epithelial tissues and their movements.

About the speaker:

Dr. Rizvi obtained B.Tech from BSBE Department of IITK. After a very brief tenure at Global Analytics, Chennai he joined for M Tech program at IIT Kanpur in BSBE Department. He converted his program to PhD under Late Prof. Anupam Pal and eventually finished it under Prof. Sovan L Das of ME. During his PhD he worked on Mechanics of Bio-membranes. Presently, he is working as a CNRS post-doctoral fellow with Chaouqi Misbah and Alexander Farutin at Grenoble in France.

Abstract:

In August 2014 the ESA spacecraft Rosetta encountered the comet 67P/Churyumov-Gerasimenko. The overall objective of the Rosetta mission was to determine physical and chemical properties of comet 67P. The orbiter of Rosetta was itself an instrument platform. It also carried the lander Philae that landed on the comet’s nucleus on November 12th 2014. Philae had ten different instruments on board including the Surface Electric Sounding and Acoustic Monitoring Experiment (SESAME) comprising CASSE, DIM, and PP. The mission ended on September 30th, 2016 when the orbiter was landed on the comet as well. The Comet Acoustic Surface Sounding Experiment (CASSE) is housed in the soles of Phi-lae’s landing-gear feet. The acceleration signals at the first landing site Agilkia occurring in the first seconds of the touchdown at an impact velocity of approx. 1 m/s was recorded by CASSE. The inversion of the data based on the transfer function of the landing gear and the foot soles yielded the compression strength and the elastic modulus of the cometary soil. Both the compression strength and the elastic modulus of the surface of comet 67P are very low compared to commonly used engineering materials. The accelerometers of the SESAME/CASSE instrument recorded surface waves at the final landing site Abydos generated during the MUPUS (“Multi-Purpose Sensors for Surface and Sub-Surface Science”) hammering phase. Group arrival time differences between the three feet of Philae were measured and the Rayleigh wave was derived. From the frequency-dependent dispersion of the signals, one can conclude that the surface of comet 67P at Abydos is layered. The Dust Impact Monitor (DIM) on board of Philae is a cube with PZT detectors. DIM was aimed to derive the elastic-plastic properties and the flux of the millimeter-sized dust-particle population that moves near the surface of the comet nucleus. During the descent phase of Phi-lae, a signal was recorded by a dust particle and its diameter and elastic modulus was derived. The SESAME-PP instrument is an impedance probe with which the resistivity, i.e. the die-lectric response near the surface was measured. In this presentation, an overview on the course of the Rosetta mission is given and data rec-orded by CASSE, DIM and PP are presented. The mechanical and the dielectric properties of the comet material correspond to very porous solids with porosities up to 80% and of agglomerates of regolith particles. A part of the CASSE instrument was developed at the Fraunhofer Institute for Non-Destructive Testing in Saarbrücken where the speaker was employed until retirement. Fi-nally, the SESAME measurement techniques used on comet 67P are briefly compared to those used in non-destructive materials characterization.

About the speaker:

W. Arnold obtained a diploma in physics (equivalent to a master degree) in 1970 and a PhD in Solid State Physics in 1974 both from the Technical University Munich, Germany. He then held various positions as a researcher in Solid State and Applied Physics in academia and industry in France, USA, Switzerland, and in Germany. From 1980 until retirement end of 2007 he was employed at the Fraunhofer IZFP, Saarbrücken as a department head developing and applying methods for non-destructive materials characterization. W. A. was appointed professor of materials technology in 1989 at the Saarland University. W.A. guided 151 undergraduate students in their diploma, master thesis and study projects and till now 33 PhD’s. Parallel he served in various scientific committees, for example from 2001 to 2014 in the selection committees of the Alexander von Humboldt foundation. W.A. is a fellow of the Institute of Physics in London and an honorary member of Indian Society of Non-Destructive Testing in Delhi. Since 2009 he is a guest professor at the I. Physikalische Institut, Georg-August Universität Göttingen, Germany and in addition works as a self-employed consultant.

Abstract:

Biological growth necessarily involves mass addition in bodies leading to microstructural rearrangements and internal stress distributions. It can be classified as either volumetric, surface, or interfacial based on the nature of mass exchange with the external environment. Whereas mass is added in the bulk material during volumetric growth (e.g., soft tumorous and arterial tissues), it accretes on to a free surface of the body during surface growth (e.g., hard horn and bone tissues), and to a material or a non-material interface within the body during interfacial growth (e.g., ring formation in trees and healing of cutaneous animal wounds). In the first part of this talk, a general theory of thermodynamically consistent biomechanical-biochemical growth, considering mass addition in the bulk and at an incoherent interface, will be presented. The incoherency arises due to incompatibility of growth and elastic distortions at the interface. The biochemicals in the model are essentially represented by nutrient concentration fields and a nutrient balance law is postulated which, combined with mechanical balances and kinetic laws, yields an initial-boundary-value problem coupling the evolution of bulk and interfacial growth, on one hand, and the evolution of growth and nutrient concentration on the other. In the second part, we will discuss the solution of the posed problem for two distinct examples: healing of cutaneous wounds in animals and annual ring formation during tree growth. In the former, the biomechanical growth model is used to study the proliferation stage of cutaneous wound healing while emphasizing the emergence of stress along with instabilities such as wrinkling and rupturing in the skin and the wound. We also calculate the nutrient concentration field during the healing process. In the second example, we will calculate the growth stress and nutrient concentration distributions in trees as a result of annual ring formation. We will also use bark elasticity to correlate the crack patterns on the bark with the growth strains therein.

About the speaker:

Dr. Anurag Gupta, Dept. Mechanical Engineering, IITK.

Abstract:

Craya-Herring basis is very useful for describing incompressible fluid flows. It exploits the fact that in the Fourier space, the velocity vectors lie in the plane perpendicular to the wavenumber vector. In this pedagogical talk I will describe how this basis function helps us derive long instability computations in a relatively simpler way. In this basis, we do not need the stream function. We will work out the instabilities in thermal convection, rotating thermal convection, and magneto-convection.

About the speaker:

Prof. Mahendra Verma, Physics Dept., IITK.

Abstract:

Diesel engine emissions of oxides of nitrogen and particulate matter can be reduced simultaneously through the use of high levels of exhaust gas recirculation (EGR) to achieve low temperature combustion (LTC). Although the potential benefits of diesel LTC are clear, the main challenges to its practical implementation are the requirement of EGR levels that can exceed 60%, high fuel consumption, and high unburned hydrocarbon and carbon monoxide emissions. These limit the application of LTC to medium loads. In order to implement the LTC strategy in an on-road vehicle application, a transition to conventional diesel operation is required to satisfy the expected high load demands on the engine. The investigation was therefore aimed at improving the viability of the high-EGR LTC strategy for steady-state and transient operation and this would be core of the presentation. In this presentation, the research work carried out on a single cylinder high-speed direct injection diesel engine will be presented and discussed in terms of engine in-cylinder performance and engine-out gaseous and particulate emissions at operating conditions (i.e. EGR rate, intake pressure, fuel quantity, injection pressure) likely to be encountered by an engine during transient and steady-state operation. At selected operating points, further investigation in terms of in-cylinder spray and combustion visualization, flame temperature and soot concentration measurements will be provided in order to get deeper insight into the combustion and emissions phenomena. Increased intake pressure at single injection and split fuel injection will be presented as strategies to reduce the emissions of partial combustion by-products and to improve fuel economy in the high-EGR LTC operation. The higher intake pressure, although effective in reducing partial combustion by-products emissions and improving fuel economy, increased the EGR requirement to achieve LTC. A split fuel injection strategy with advanced injection timing on the other hand was effective in reducing the EGR requirement for LTC from 62% with single injection to 52% with split injections. The difficulties associated with drivability, emissions and fuel economy during a load transient necessitating a combustion mode transition at a constant speed will also be presented. A future outlook outlining research proposals in low temperature combustion will be discussed.

About the speaker:

Dr Asish Sarangi is currently working as a Senior Engine Development Engineer in JCB Power Systems, UK. JCB is a leading firm that develops many of their engine systems for off-road equipment: his current role covers all aspects of engine development from engine modelling to combustion and exhaust after-treatment system development. Dr Sarangi completed PhD in Mechanical Engineering from Loughborough University, UK where he worked on his PhD thesis entitled “Diesel Low Temperature Combustion – An Experimental Study” under the supervision of Professor Colin Garner and Dr Gordon McTaggart-Cowan. For pursuing his PhD, Asish has been the recipient of Loughborough University Departmental Scholarship with support from the UK Engineering and Physical Sciences Research Council. Dr Sarangi did his postdoctoral work at the Future Engines and Fuels Lab in The University of Birmingham, working on gasoline direct injection combustion and the effects of fuel additive, bio-fuel contents and fuel quality on injector deposit formation. Prior to joining PhD, Asish worked in Honeywell, Bangalore on the thermodynamic simulation of turbochargers, and in National Aerospace Laboratories Bangalore on the mechanical aspects of turbo-machineries, rotor dynamics and the development of high-speed foil air bearings. He completed his undergraduate degree in Mechanical Engineering from Utkal University Odisha and subsequently his MS (by Research) degree in Mechanical Engineering with specialisation in IC Engines from IIT Madras Chennai. For his MS thesis, Asish worked under the guidance of Professor Pramod Mehta and Professor A. Ramesh on the evaluation of performance, combustion and emission characteristics of a mini IC engine used in unmanned air vehicles. He received the Junior and Senior Research Fellowships of CSIR India to pursue his MS degree.Asish has authored and co-authored over 10 journal and conference papers.

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.

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

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.

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.