Prof Dhrubaditya Mitra's Talk

Aug 09, 2018 - 17:00

Aug 09, 2018 - 18:00

Room 118 Chemical Engg Dept

Seminars

Prof Dhrubaditya Mitra NORDITA Sweden

Abstract: Although we teach our students mostly about Newtonian fluids most of the fluids that we meet in real life e.g. Mumbai road after monsoon rains are complex fluids. A model of complex fluids is objects (often spheres) immersed in a Newtonian fluid. We numerically solve this model to calculate rheology at moderate strain-rates and volume-fraction (occupied by the immersed objects) for three different cases : (a) rigid spheres immersed in a plane Couette flow[1]; (b) rigid spheres confined within thin (a few sphere-diameters) channel[2] (c) soft spheres in plane Couette flows[3]. In the first case we find that the data on effective viscosity can be collapsed to an universal function of a combination of the volume-fraction and strain-rate. The same universal function also works in the third case but the function is then a function of a combination of the volume-fraction and the elastic coefficient of the spheres. In the second case we show that if the thickness of the confining channel is a small integer multiple of the diameter of the the spheres the viscosity decreases significantly. Refs: [1] "Shear Thickening in Non-Brownian Suspensions: An Excluded Volume Effect" Francesco Picano Wim-Paul Breugem Dhrubaditya Mitra and Luca Brandt Phys. Rev. Lett. 111 098302 (2013) [2] "Rheology of Confined Non-Brownian Suspensions" Walter Fornari Luca Brandt Pinaki Chaudhuri Cyan Umbert Lopez Dhrubaditya Mitra and Francesco Picano; Phys. Rev. Lett. 116 018301 (2016) [3] Rheology of suspensions of viscoelastic spheres: Deformability as an effective volume fraction Marco E. Rosti Luca Brandt and Dhrubaditya Mitra Phys. Rev. Fluids 3 012301(R) (2018)Bio: Prof Mitra completed his M.S. and Ph. D. in Physics from IISc. He was subsequently a Leverhume trust post-doctoral fellow at University of London and Henri Poincare post-doctoral fellow at Observatoire de la Cote d'Azur Nice France. He is currently serving as an Assistant Professor at Nordic Institute for Theoretical Physics (NORDITA). His research interests include: Soft-Matter; rheology of suspensions cells and membranes in flows. Turbulence; dynamics of turbulence and particles in turbulent flows. Astrophysics; solar physics dynamos and magnetohydrodynamics. Numerical Techniques Large scale parallel simulations. This seminar is compulsory for students registered for course CL 702 or CL 704.