Regensburg 2010 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 26: Micro and Nanofluidics I

CPP 26.12: Vortrag

Mittwoch, 24. März 2010, 17:00–17:15, H39

Dynamics of trapped Brownian particles in shear flows: shear-induced cross-correlations — •Jochen Bammert and Walter Zimmermann — Theoretische Physik I, Universität Bayreuth, 95440 Bayreuth

Shear flow causes cross-correlations between fluctuations along orthogonal directions of Brownian particle motion. This effect has been measured recently in an experiment [1], where one or two polystyrene beads were trapped by optical tweezers in a specially designed shear flow cell (see also the contribution of A. Ziehl et al.). The results coincide with the predictions of a Langevin model as explained by this contribution and in [2], where the dynamics of a Brownian particle trapped by a harmonic potential and simultaneously exposed either to a linear shear flow or to a plane Poiseuille flow is described. In the shear plane of both flows the probability distribution of the particle becomes anisotropic and takes either an elliptical or a parachute shape or a superposition of both depending on the mean particle position in the shear plane. We have also determined the correlations between two trapped and hydrodynamically interacting particles in a linear shear flow. Again, correlations between orthogonal directions in the shear plane are found, even between different particles.

[1] A. Ziehl, J. Bammert, L. Holzer, C. Wagner, W. Zimmermann, arXiv:0909.0401, to appear in Phys. Rev. Lett.

[2] L. Holzer, J. Bammert, R. Rzehak, W. Zimmermann, arXiv:0911.3264, submitted to Phys. Rev. E