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DY: Fachverband Dynamik und Statistische Physik

DY 45: Brownian Motion and Anomalous Transport - organized by Ralf Metzler (Potsdam)

DY 45.7: Talk

Wednesday, March 24, 2021, 16:10–16:30, DYc

Dynamics of a point-like colloid in a confined critical fluid — •Markus Gross — MPI for Intelligent Systems, Stuttgart

We study analytically and via simulations a point-like colloidal particle (tracer) immersed in a confined critical fluid. Particle and fluid are governed by a system of coupled stochastic PDEs. In addition to a white noise, the particle experiences a random force due to the coupling to the fluctuating fluid density, which is spatially correlated and strongly non-Markovian. By adiabatically eliminating the fluid degrees of freedom, we obtain an effective Langevin equation for the particle, which entails a fluctuation-induced (Casimir) potential, a spatially dependent Markovian noise, and a spatially dependent mobility. The stochastic interpretation of the noise is found to depend on the type of coupling between particle and fluid.

Reference: M. Gross, arXiv:2101.02072