Berlin 2005 – scientific programme

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DY: Dynamik und Statistische Physik

DY 34: Poster

DY 34.43: Poster

Monday, March 7, 2005, 15:30–18:00, Poster TU D

Synchronization of rotating helices by hydrodynamic interactions — •Michael Reichert and Holger Stark — Universität Konstanz, Fachbereich Physik, D-78457 Konstanz, Germany

Some types of bacteria use rotating helical flagella to swim. The motion of such organisms takes place in the regime of low Reynolds numbers where viscous effects dominate and where the dynamics is governed by hydrodynamic interactions. Typically, rotating flagella form bundles, which means that their rotations are synchronized. The aim of our study is to investigate whether hydrodynamic interactions can be at the origin of such a synchronization.

We consider two stiff helices that are modelled by rigidly connected beads, neglecting any elastic deformations. They are driven by constant and equal torques, and they are fixed in space by anchoring their terminal beads in harmonic traps. We observe that, for finite trap strength, hydrodynamic interactions do indeed synchronize the helix rotations. The speed of phase synchronization decreases with increasing trap stiffness. In the limit of infinite trap stiffness, the speed is zero and the helices do not synchronize. This limit is consistent with recent work by Kim and Powers based on slender-body theory [Phys. Rev. E 69, 061910 (2004)].