Bhargav Rallabandi

Particle hydrodynamics near deformable interfaces

Interactions of suspended particles with flexible structures are important in many natural and engineered systems including examples in lubricated bearings, blood flow, and microfluidics. In the first part of my talk, I will focus on a microfluidic application that uses ultrasound-driven bubbles to either sort or trap microparticles by size. I will present a predictive model that shows that particle sorting and trapping result from an interplay between the particle’s inertia and hydrodynamic interactions with the oscillating bubble interface. I will go on to discuss limiting cases of strong and weak interactions which recovers results from geometry and acoustics, respectively. The second part of the talk addresses situations where interface deformation, mediated by hydrodynamic interactions, is a direct consequence – and a subsequent cause – of particle motion. I will present experiments demonstrating that rigid particles translating near a flexible elastic membrane are repelled by it due to hydrodynamic interactions. A model of these interactions involving membrane tension and bending will then be discussed, leading to a description of particle hydrodynamics near more general deformable surfaces. The results suggest that similar interactions may play a role in blood flow and cellular processes at the microscale.

Bhargav Rallabandi holds a B.S. degree in Mechanical Engineering from the National Institute of Technology Karnataka, and M.S. and Ph.D. degrees in Theoretical and Applied Mechanics from the University of Illinois at Urbana-Champaign. After a period of postdoctoral work at Princeton University, he joined the Mechanical Engineering faculty at the University of California, Riverside in 2018. His current research focuses on particulate transport in fluids, including microscale acoustics, fluid-elastic interactions, and colloidal self-propulsion. He is a recipient of the 2020 Hellman Fellowship