Regensburg 2022 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 45: Poster Session: Nonlinear Dynamics, Pattern Formation, Data Analytics and Machine Learning
DY 45.4: Poster
Donnerstag, 8. September 2022, 15:00–18:00, P2
Spontaneous vortex formation by microswimmers with retarded attractions — Xiangzun Wang1, •Pin-Chuan Chen2, Klaus Kroy2, Viktor Holubec3, and Frank Cichos1 — 1Peter Debye Institute for Soft Matter Physics, Leipzig Univeristy, Leipzig, Germany — 2Institute for Theoretical Physics, Leipzig University, Leipzig, Germany — 3Department of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic
In recent experiments done in the Molecular Nanophotonics Group in the Peter Debye Institute, thermophoretic microswimmers are observed to self-assemble into bi-stable rotational modes due to retarded attractive interactions. For the particular case where a single swimmer is attracted to an immobilized target, we show how we can analytically understand such non-linear stochastic time-delayed system. This could be achieved by Taylor expanding the equation for small time delay. The system can then be described by an overdamped Langevin equation with a potential determined by time delay, and the transition in between the two stable modes is well predicted by Kramers' escape rate. We further show results of simulations extended to 3 dimensions and that of an alternative model in 2 dimensions. Both extensions show that with simple delayed interaction rules and volume exclusion effects, rich many-body behaviors emerge with various patterns depending on the time delay.