Dispersion of suspended particles in a wave boundary layer over a viscoelastic bed

Abstract

This is an analytical study with an aim to show the effects of a viscoelastic muddy bottom on the wave-induced convection and dispersion of a dilute suspension in the wave boundary layer above the viscoelastic bottom. It is shown that, depending on the rheology of the mud, the convection velocity and dispersion coefficient are non-monotonic functions of the thickness of the mud layer. When the elasticity dominates, appreciable resonant amplification of the mud motion can happen to a layer of certain thickness, which may lead to an order of magnitude increase in the dispersion coefficient and a negative convection velocity as well. It is, however, also possible that, away from these resonant mud depths, the convection velocity and dispersion coefficient are diminished, even to the extent to become virtually zero. All these transport phenomena are related to the oscillatory movement of the water-mud interface, in terms of phase and amplitude, relative to the movement of the near-bottom water particles. © 2007 Elsevier Ltd. All rights reserved.