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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 41: Colloids and Complex Liquids I

CPP 41.5: Vortrag

Donnerstag, 14. März 2013, 11:00–11:15, H40

Two-dimensional active Brownian motion of asymmetric microswimmers — •Borge ten Hagen¹, Felix Kümmel², Raphael Wittkowski¹, Ivo Buttinoni², Giovanni Volpe³, Clemens Bechinger^2,4, and Hartmut Löwen¹ — ¹Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf — ²2. Physikalisches Institut, Universität Stuttgart — ³Department of Physics, Bilkent University, Cankaya, Ankara, Turkey — ⁴Max-Planck-Institut für Intelligente Systeme, Stuttgart

We study the Brownian dynamics of asymmetric self-propelled particles in two dimensions. In our theoretical model based on the Langevin equations the propulsion mechanism is taken into account by means of an effective internal force. For asymmetric particles a non-central drive and translation-rotation coupling lead additionally to an effective intrinsic torque. When external forces are neglected, such particles move on a circular trajectory and the noise-averaged trajectory is predicted to be a logarithmic spiral. Under gravity several qualitatively different types of motion are found: Either a straight downward or upward motion (gravitaxis) occurs or the particle describes a periodic circling motion. Our theoretical description, which is very general and holds for arbitrarily shaped microswimmers, is verified in experiments with L-shaped model swimmers.