Modeling of Sediment Transport with a Mobile Mixed-Sand Bed in Wave Motion

Abstract

A multilayer model is proposed to calculate time-dependent sediment velocity and concentration profiles with the resulting sediment transport. The model is developed here for the wave boundary layer. Measurable quantities are considered, namely, the values of transport during the wave crest and the wave trough, as well as total and net sediment transport values (averaged over the wave period) resulting from the summation and subtraction of their absolute values, respectively. The calculated value of the maximum stress at the bed during the wave period is verified by direct stress measurements. The model is tested for mixed sediments with different grain size distributions including semiuniform and poorly sorted grains. Transport calculations are carried out for acceleration-skewed oscillatory flows and waves described by Stokes’ first and second approximations. Comparison with the available small- and full-scale data from flumes and oscillating tunnels yields agreement typically within plus/minus a factor of two of the measurements.