The study of microparticles (particles of sizes in microns) in a fluid has a rich and distinguished history. Einstein and Perrin showed that the Brownian motion of microparticles is striking proof of the graininess (molecular nature) of the surrounding fluid. Active particles (e.g., microorganisms and Janus particles) are a class of microparticles that can create flow in the surrounding fluid, even when stationary, due to non-equilibrium processes on their surfaces. In this talk, I will describe a theoretical method to obtain an explicit expression for fluid-mediated forces and torques between active particles and a corresponding numerical technique implemented in PyStokes, a freely available open-source library on GitHub. The combined analytical and numerical approach allows for studying the statistical mechanics of active particles with phoretic and hydrodynamic interactions in distinct experimental settings to derive testable predictions. I will use these results to explain mechanisms for recent experimental phenomena in active matter.
Dr. Rajesh Singh completed his Ph.D. from IMSc, Chennai, in 2018. Between 2018-21, he was a postdoc in the Department of Applied Mathematics and Theoretical Physics, University of Cambridge. Dr. Rajesh joined the Department of Physics, IIT Madras, in October 2021. His research interests are in the field of theoretical soft condensed matter physics. With this principal theme, he studies problems in statistical mechanics, fluid mechanics, computational physics, biophysics, and Bayesian statistics. His current research focuses on the nonequilibrium statistical mechanics of active and driven systems.