Regensburg 2019 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 44: Active Matter C (joint session DY/CPP)

DY 44.10: Talk

Thursday, April 4, 2019, 12:30–12:45, H19

Diffusion of active particles in a complex environment: role of surface scattering — •Theresa Jakuszeit, Ottavio A. Croze, and Samuel Bell — Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, U.K

Microfluidic experiments have shown that self-propelled particles can slide along the surface of a circular obstacle without becoming trapped over long times for obstacles below a critical radius. Using simulations and theory, we study the impact of different boundary conditions on the diffusive transport of active particles in a lattice of such obstacles. We find that particle dynamics with sliding boundary conditions can result in large diffusivities even at high obstacle density, unlike classical specular reflection as in the Lorentz gas. These dynamics are very well described by a model based on Run-and-Tumble particles with microscopically derived tumbling frequencies and reorientation functions arising from obstacle-induced tumbles. This model, however, fails to describe fine structure in the diffusivity at high obstacle density predicted by simulations. Using a simple deterministic model, we show that this structure results from particles being guided by the lattice.