Sediment Transport in Random Waves at Constant Water Depth

Abstract

Sediment transport in random waves at constant water depth is analyzed by dividing the flow field into two regions—the internal region and the boundary layer region. The suspension and transport of sediment in these two regions are treated separately. The total transport is then obtained as the total of these regions through matching boundary. In the bed layer, the load concentration is assumed to be proportional to the specific weight of the sediment and to the probability that the fluctuating lifting force exceeds the weight of the sediment. The bed load is then transported by the secondary flow (which is unidirectional) in the boundary. In the internal flow region, the sediment suspension is treated as a diffusion problem with the intensity of diffusion to be proportional to the amplitude of fluid particle motion. The transport velocity is assumed to be the same as the mass transport velocity of the wave. The predominant mode of transport is found to be suspended load. The total transport in a wind-generated wave field can be expressed as a power law of wind speed. For the case tested, the power should be of the order of 4.