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DY: Fachverband Dynamik und Statistische Physik
DY 24: Focus Session: Broken Symmetries in Statistical Physics - Dynamics of Odd Systems
DY 24.11: Hauptvortrag
Mittwoch, 19. März 2025, 18:00–18:30, H43
How to model frictional contacts in sheared and active colloids — •Friederike Schmid1, Kay Hofmann1, Kay-Robert Dormann2, and Benno Liebchen2 — 1Johannes Gutenberg Universität Mainz — 2Technische Universität Darmstadt
In simulations of colloidal matter, frictional contacts between particles are often neglected. For spherical colloids, such an approximation may have a significant impact on the results in certain situations (e.g., colloids under shear, chiral active matter), since frictional contacts induce a coupling between translational and orientational degrees of freedoms of particles which is otherwise absent. Models for implementing frictional contacts have been proposed in the granular matter community. Owing to the large size of granular particles, these models do not include thermal noise. On the colloidal scale, thermal fluctuations are important and should be incorporated in a thermodynamically consistent manner.
In the present talk, we show how to derive the correct fluctuation-dissipation relation for frictional contacts with arbitrary - linear or nonlinear - relation between the friction force and the relative velocity at the contact point, and how to implement the corresponding stochastic force terms. Among other this results in a new generalized class of dissipative particle dynamics (DPD) thermostats with rotation-translation coupling. Possible effects of frictional contact interactions are demonstrated using the example of Poiseuille flow and motility induced phase separation in active Langevin particles.
Keywords: colloids; chiral active matter; dissipative particle dynamics; fluctuation dissipation relation; shear