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Friday, October 7, 2011

Hydrodynamic Pair Attractions between Driven Colloidal Particles

Yulia Sokolov, Derek Frydel, David G. Grier, Haim Diamant, and Yael Roichman

Colloidal spheres driven through water along a circular path by an optical ring trap display unexpected dynamical correlations. We use Stokesian dynamics simulations and a simple analytical model to demonstrate that the path’s curvature breaks the symmetry of the two-body hydrodynamic interaction, resulting in particle pairing. The influence of this effective nonequilibrium attraction diminishes as either the temperature or the stiffness of the radial confinement increases. We find a well-defined set of dynamically paired states whose stability relies on hydrodynamic coupling in curving trajectories.

DOI

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