Berlin 2015 – scientific programme

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BP: Fachverband Biologische Physik

BP 20: Microswimmers, Active Liquids II (joint DY/BP/CPP)

BP 20.1: Talk

Tuesday, March 17, 2015, 09:30–09:45, BH-N 128

Trapping of active particles in inhomogeneous systems — •Martin P. Magiera, Kevin Schröer, and Lothar Brendel — Fakultät für Physik, Universität Duisburg-Essen

Inhomogeneities in a system containing active particles can lead to an inhomogeneous particle distribution if they influence the particles’ velocities [Schnitzer, PRE 48, 2553]. Those may be caused, e.g., by inhomogeneous tumble rates of bacteria or inhomogeneous drive of men-made microswimmers [e.g. Buttinoni et al, PRL 110, 238301].

Using Brownian dynamics simulations we show that such inhomogeneities can lead to particle accumulation in a prescribed passivity region where the activity of particles is suppressed, an effect interesting for applications. We derive a corresponding accumulation parameter with an extended Fick’s law for inhomogeneous systems. Depending on the overall particle density a complete particle trapping can be observed. However, even if only a minority of particles is trapped, a tiny yield can act as a nucleation seed for larger agglomerates generated by dynamical clustering [Fily and Marchetti, PRL 108, 235702] and pinned to the passivity region.