Hydrodynamic interactions in quasi-two-dimensional colloidal suspensions

The effects of the hydrodynamic interactions on the short-time dynamics of colloidal, hard-sphere-like particles confined between two parallel walls are measured by digital videomicroscopy. We find that such effects can be described in terms of an effective two-dimensional hydrodynamic function H(k), defined as a straightforward adaptation to two dimensions of the corresponding object describing collective dynamics for the three-dimensional (3D) suspensions. Interestingly, the behavior of H(k) is qualitatively similar to the hydrodynamic function of 3D suspensions of hard spheres. We also found that for values of k where the static structure factor is 1, the dynamics is determined only by self-diffusion. © 2001 American Physical Society.

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