Regensburg 2007 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 24: Micro and Nano Fluidics II: Soft Objects in Flow + Slippage

CPP 24.3: Talk

Thursday, March 29, 2007, 10:15–10:30, H37

Brownian dynamics of microswimmers — •Vladimir Lobaskin — Physics Department T37, Technical University of Munich, 85747 Garching, Germany

We perform computer simulation of few simple model microswimmers consisting of three spheres and propelling themselves in a fluid by non-reciprocal body reshaping cycle at low Reynolds numbers. We find that the stationary velocity of the swimmers can be described by an universal scaling law and grows as a square of the beating amplitude and linear in the beating frequency. We show that the performance of coupled swimmers scales linearly with their number. In presence of fluctuations, the microswimmers display random walk trajectories. The characteristics of the trajectory and the velocity distribution change qualitatively upon variation of the stationary swimming velocity at fixed temperature. We observe a Gaussian random walk and Maxwellian velocity distribution in the weak-beating regime and crater-like velocity distribution, typical for driven systems, in the strong-beating regime. The transition to the driven regime as well as the corresponding force-velocity relation for the microswimmers can described by a Langevin theory of active Brownian motion.