Spring 2015
Seminars are held on Mondays from 1:30 - 2:30PM in Cullimore Hall, Room 611, unless noted otherwise. For questions about the seminar schedule, please contact David Shirokoff.
Date: May 4, 2015
Speaker: Tony Gao
Courant Institute of Mathematical Sciences,
New York University
Title: "Modeling and Simulation in Complex Fluids: From Passive to Active Systems"
Abstract:
Complex fluids, which are multi-component mixtures, often exhibit non-Newtonian behavior in response to external loading, due to constituents' material properties, local heterogeneity in microstructures, and particle-particle interactions. When the constituents are self-driven, the systems can be spontaneously out of equilibrium. They orchestrate cooperative actions and exhibit rich dynamical behavior featuring collective motion accompanied by energy conversion. In this talk, I discuss recent studies on modeling and the simulation of both passive and active complex-fluids systems in order to understand their physical properties. First, the dynamics and rheology of soft elastic particles in viscous flows are discussed. I introduce a novel monolithic arbitrary-Lagrangian-Eulerian finite element method that allows the velocity, pressure and stress field in the fluid and particles to be solved simultaneously. I further demonstrate that at low Reynolds number, the finite-strain, time-dependent response of elastic particles can be solved analytically using a polarization technique originally developed for the classical Eshelby problem in linear elasticity. Second, a bio-active fluid composed of microtubule/motor protein assemblies is examined using a multiscale model combining the discrete particle method and continuum kinetic theory. I explain how local microtubule-motor and microtubule-microtubule interactions manifest themselves at macroscopic scales through hydrodynamic instability, and describe the connections between the topological defects in active nematics and coherent flow structures.