Berlin 2018 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 32: Microswimmers I (joint session DY/BP/CPP)

DY 32.2: Vortrag

Dienstag, 13. März 2018, 14:15–14:30, BH-N 243

Dynamics of a single circular microswimmer in a quenched crowded media — •Oleksandr Chepizhko and Thomas Franosch — Institute for Theoretical Physics, University of Innsbruck, Innsbruck, Austria

The motion of active particles, for example, bacteria or unicellular organisms, in nature occurs in crowded environments such that the walls, boundaries, and obstacles strongly influence the dynamics of the microswimmers. Here we present a generic model for a deterministic circular microswimmer in a disordered two-dimensional quenched random array of obstacles. The microswimmer moves in circular orbits between the collisions with the obstacles, and after colliding with an obstacle the microswimmer follows the obstacle's surface for some time before detaching again.

The diffusivity of the system is studied via event-driven computer simulations for a wide range of obstacle densities and orbit radii. We find to phase boundaries of a conducting phase with an insulating and a localized phase. The phase behavior is investigated both close to these two transition lines, as well as deep in the conducting phase. The phase transitions correspond to critical phenomena with both an underlying static percolation transition, while the dynamic exponents reveal different universal classes. Furthermore, we find that the diffusivity grows with the density of obstacles up to a narrow region in the vicinity of the localization transition where it rapidly drops to zero.