Stochastic Stokes' Drift
Physical Review Letters
81 3136 (1998)
Kalvis M Jansons
Department of Mathematics, University College London.
Gower Street WC1E 6BT, England.
Grant D Lythe
Departamento de Matemáticas
Universidad Carlos III de Madrid
Avenida de la Universidad 30
28911 Leganés, Madrid, Spain
Classical Stokes' drift is the small time-averaged drift
velocity of suspended non-diffusing particles in a fluid due to the
presence of a wave. We consider the effect of adding diffusion to the
motion of the particles, and show in particular that a non-zero
time-averaged drift velocity exists in general even when the classical
Stokes' drift is zero. Our results are obtained from a general
procedure for calculating ensemble-averaged Lagrangian mean velocities
for motion that is close to Brownian, and are verified by numerical
simulations in the case of sinusoidal forcing.