Aug 2: Seminar on Flow control past bluff bodies

Dr. Sanjay Kumar, Associate Professor at Department of Engineering, University of Texas at Brownville, USA would be presenting a seminar in the department as per the following schedule.

Speaker:  Dr. Sanjay Kumar
Title:         Flow control past bluff bodies 
Date  :      Friday, August 2, 2013
Time  :      04:00 PM
Venue :    AE seminar room

Tea would be served at 3:45PM.

Abstract

Study and control of wake structure behind bluff bodies has several engineering applications. Some areas where knowledge of vortex shedding behind bluff bodies becomes important are: flow induced vibrations, acoustic noise, fluid mixing, among several others. The present talk will focus on presenting some of our recent experimental results on two investigations involving control of wake structure past a very simple bluff body – a circular cylinder, by controlled surface motion. In the first problem we study the classical problem of flow past a rotating cylinder (J. Fluids Engg. (2011)). In this work we present changes in the wake structure at various speeds of cylinder rotation at Reynolds number, Re, of 200 and for the first time show a clear evidence of new vortex shedding mode which occurs at sufficiently high cylinder rotation rates after the regular vortex shedding has been suppressed. In the second problem, we investigate flow past a rotationally oscillating cylinder with focus on lock-on (to appear in
J. Fluid Mech. (2013)) at Reynolds numbers of 185 and 400. It is found that the wake lock-on depends not only on the forcing amplitude/frequency but also on the downstream extent. The circulation measurements reveal a universal decay curve with forcing frequency, independent of forcing amplitude, beyond Strouhal forcing and a scaling behavior with forcing amplitude at lesser forcing frequencies. In addition, we find a very interesting result that the far wake (~ 35 to 40 diameters downstream) can be forced to become two dimensional by rotational oscillations in certain forcing parameter range at Re = 400 thereby providing significant control on fluid mixing.

About the Speaker

Education:   B.Tech (Aersopace Engineering) 1994 - IIT/K
                    M.Tech (Aerospace Engineering) 1996 - IIT/K
                    P.hD (Aeronautics) 2003 - Cal Tech.

Professional Experience: 2003 - 2006: Post-doctoal fellow at the Los Alamos National Laboratory, Los Alamos, NM (USA).

2006 - 2011: Assistant Professor Department of Engineering, University of Texas at Brownville, Texas
2011 - present: Associate Professor Department of Engineering, University of Texas at Brownville, Texas.

Research Interests: Shock accelerated flows, Wakes, Fluid Instabilities.