Regensburg 2007 – scientific programme

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BP: Fachverband Biologische Physik

BP 27: Nonequilibrium Processes and Self-Organisation

BP 27.3: Talk

Friday, March 30, 2007, 11:15–11:30, H43

Directed Brownian motion of non-spherical particles — •Susan Sporer, Christian Goll, and Klaus Mecke — Institut für Theoretische Physik, Universität Erlangen-Nürnberg, Staudtstrasse 7, 91058 Erlangen

Mesoscopic particles, such as molecular motors, embedded in a fluid are expected to perform symmetric thermal fluctuations around a mean position. A net transport in a preferred direction is not possible in thermal equilibrium without applying a temperature gradient or an external force which breaks the spatial symmetry. However, directed Brownian motion is possible if the particle is a-symmetric and the system is prohibited from relaxation in thermal equilibrium. A non-equilibrium state can be sustained by stopping the particle at periodic sites along a filament. After releasing the relaxation process towards a Maxwellian velocity distribution has a preferred direction which causes a directed motion due to the particle asymmetry. Even motion against a small fluid drift is possible. The relaxation process, the directed motion and its dependence on the particle shape are analyzed analytically. The results are compared to molecular dynamics simulations.