Stokes' drift: a rocking ratchet

Abstract

We derive the explicit analytic expression for the Stokes' drift in one dimension in the presence of a dichotomic Markov forcing. For small amplitudes of the forcing, the drift is enhanced, but the enhancement is reduced with increasing frequency of the forcing. On the other hand, a reduction of the drift or even a flux reversal can be induced at larger amplitudes, while the flux is now found to be an increasing function of the perturbation frequency.

9 pages, 3 PostScript figures; accepted for publication in J. Stat. Phys.; One new figure has been added, showing the change of drift direction in 2D