INSTITUTE COLLOQUIUM – by Prof. Jaywant H Arakeri

Location: Faculty Hall


Speaker : Professor Jaywant H Arakeri
Department of Mechanical Engineering

Topic :

  • Part 1. Tube convection – a new type of turbulent flow.
  • Part 2. Fluid mechanics of fish swimming

Date : 28th Jan 2020. 4.00 pm
Venue : Faculty Hall, Main Building, IISc

Prof. Anurag Kumar, Director, IISc., will preside

Abstract : Turbulent flows are ubiquitous, highly complex and important from both fundamental and application viewpoints. Much of the understanding of turbulent flows has come from studying relatively simple prototype flows like that in a long straight constant-cross section pipe. I am going to talk about one such flow on which we have been working on for several years – axially homogeneous, purely buoyancy driven turbulent convection in a long vertical tube. Tube convection is very different from Rayleigh-Benard convection, the much studied standard prototype convective flow. In particular, the turbulence in tube convection is more intense and we were able to quite easily achieve the so called ‘ultimate regime’ where heat transport is independent on viscosity and thermal diffusivity.

The second part of my talk will be on the fluid mechanics of fish swimming. Fish and other aquatic animals swim in myriad ways. In the fast swimming shark most of the motion is confined to the tail, whereas in the case of the eel a wave moves down its whole body as it swims forward. Many fish bodies and their fins and tails are highly flexible. Does flexibility make them efficient swimmers? I will discuss results of our experiments on pitching foils with a flexible tail, which show that there are two optimum stiffness coefficients one for maximizing thrust and the other for maximizing efficiency. I will touch upon an interesting question: Can we define efficiency for a self-propelling body moving at constant speed?

About the speaker : Prof Jaywant H Arakeri is in the faculty of the Mechanical Engineering department the Centre for Product Design and Manufacture at the Indian Institute of Science, Bangalore. All his education has been in aeronautical engineering, BTech (IIT, Madras), ME (IISc) and PhD (Caltech). His research is primarily focused on the fundamental understanding of various phenomena in fluid mechanics and heat transfer, in particular related to turbulence, transition to turbulence, unsteady flows, bio-fluid mechanics and evaporation from porous media. Some of the current questions being addressed in his lab relate to the role of turbulence in condensation and droplet growth in clouds; flows around flexible surfaces like fish tails and heart valves; instability of unsteady flows, including those with curvature, like those found in arteries; effect of gusts on insect flight; heat and moisture loss from soils and leaves and precision agriculture. He has written several popular science articles in Resonance. He is an Editor-in-Chief of the journal Sadhana.

All are welcome

Tea: 5.00 pm