Dresden 2014 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 39: Active Colloids

CPP 39.3: Vortrag

Donnerstag, 3. April 2014, 10:15–10:30, ZEU 260

Alignment of active particles with hydrodynamic interactions and formation of a self-assembled pump — Marc Hennes, •Katrin Wolff, and Holger Stark — Institut für Theoretische Physik, Technische Universität Berlin

Hydrodynamically interacting active particles in an external harmonic potential are known to form a self-assembled pump at large enough Peclet numbers [1]. Here, we give a quantitative criterion for the formation of the pump for active Brownian particles depending on the rotational diffusion of particles, their swim speed and the strength of the harmonic trap. The emerging flow field caused by the swimmers corresponds to a regularized stokeslet and stabilises the pump. We find that the particle distribution settles into a non-equilibrium steady state with non-vanisihing flux. The particle orientations can be mapped onto an equilibrium system as they align along a common "pump axis" in analogy to dipoles in an electric field. We perform Brownian dynamics simulations with hydrodynamic interactions and compare the many-particle simulations with an analytically tractable mean field system.

[1] R. W. Nash et al., Phys. Rev. Lett. 104, 258101 (2010)