# Regensburg 2019 – wissenschaftliches Programm

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# DY: Fachverband Dynamik und Statistische Physik

## DY 43: Anomalous diffusion / Brownian motion

### DY 43.3: Vortrag

### Donnerstag, 4. April 2019, 10:30–10:45, H3

**Ideal circle microswimmers in crowded media** — •Oleksandr Chepizhko and Thomas Franosch — University of Innsbruck, Innsbruck, Austria

Microswimmers in nature move in crowded environments and their transport properties depend in a subtle way on the interaction with obstacles. Here, we study a model for a single ideal circle swimmer exploring a two-dimensional disordered array of impenetrable obstacles. The microswimmer moves on ideal circular orbits in the freely accessible space and follows the surface of an obstacle for a certain time upon collision. Depending on the obstacle density and the radius of the circular orbits, the microswimmer displays either long-range transport or is localized in a finite region. We show that there are transitions from two localized states to a diffusive state each driven by an underlying static percolation transition. We determine the non-equilibrium state diagram and calculate the mean-square displacements and diffusivities by computer simulations. Close to the transition lines transport becomes subdiffusive which is rationalized as a dynamic critical phenomenon. Additionally, we discuss the influence of inclusion of a stochastic noise term into the equation of orbital motion.