Towards Predicting Sediment Transport in Combined Wave-Current Flow

Abstract

A one-dimensional, vertical (1DV) grid model has been developed for the prediction of sediment transport in combined wave-current flow under sheet flow conditions. The model uses a one-equation turbulence closure scheme to simulate vertical mixing processes, and a time-varying reference concentration as the bottom boundary condition for the suspended sediment layer. Comparison with recent experimental data shows that the model gives good predictions (within 30%) of the measured net sediment transport rates under different conditions. The results also demonstrate the importance of the ''wave-related'' contribution to the suspended transport, due to the unsteadiness in the velocity and sediment concentration fields. At certain elevations above the bed, the suspended flux may be in the direction opposite to that of the mean current as a result of the phase relationship between the horizontal velocity and sediment concentration.