Berlin 2012 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 12: Joint focus session (with BP): Statistics of Cellular Motion
DY 12.6: Talk
Tuesday, March 27, 2012, 12:00–12:15, H 1028
Swimming of microorganisms in a microchannel flow. — •Adam Wysocki, Roland G. Winkler, and Gerhard Gompper — Theoretical Soft Matter and Biophysics, Institute of Complex Systems and Institute for Advanced Simulation, Forschungszentrum Jülich
We consider an active suspension – motile microorganisms dispersed in a fluid – under flow in a microchannel. We use a coarse-grained model of an active suspension, where the microorganisms are modeled as spherical particles with a prescribed tangential surface velocity, and the fluid is described by multiparticle collision dynamics approach, a particle-based, mesoscopic simulation method, which includes thermal fluctuations. Our model of a swimmer can easly be tuned to be a puller or a pusher, which generate thrust in the front or at the back of the body, respectively. At low swimmer concentrations, far from the walls and for external flow fields u small compared to the propulsion velocity U0, puller and pusher swim upstream following on average a sinusoidal trajectory. Near the walls, where hydrodynamic interactions are significant, pullers and pushers show a qualitatively different behaviour. Individual pushers swim upstream near the wall for U0/u>1, while pullers swim downstream for U0/u≫1 and change to upstream swimming with increasing flow field u. The collective behaviour at higher concentrations of microorganisms will be discussed.