Dresden 2017 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 25: Posters - Soft Particles, Microswimmers, Microfluidics

DY 25.8: Poster

Dienstag, 21. März 2017, 18:15–21:00, P3

Active Brownian particles moving in a random Lorentz gas — •Maria Zeitz and Holger Stark — Institut für Theoretische Physik, Technische Universität Berlin, 10623 Berlin, Germany

Biological microswimmers often inhabit a porous or crowded environment such as soil. In order to understand how such a complex environment influences their spreading, we numerically study noninteracting active Brownian particles (ABPs) in a two-dimensional random Lorentz gas. Close to the percolation transition in the Lorentz gas, they perform the same subdiffusive motion as ballistic and diffusive particles. However, due to their persistent motion they reach their long-time dynamics faster than passive particles and also show superdiffusive motion at intermediate times. While above the critical obstacle density η_c the ABPs are trapped, their long-time diffusion below η_c is strongly influenced by the propulsion speed v₀. With increasing v₀, ABPs are stuck at the obstacles for longer times. Thus, for large propulsion speed, the long-time diffusion constant decreases more strongly in a denser obstacle environment than for passive particles.

Moreover, we present first results how a constant gradient in obstacle density influences the dynamics of the system. We expect an induced drift along the gradient, similar to the durotaxis of motile cells which move along the stiffness gradient of the substrate.