Model of Nearshore Waves and Wave-Induced Currents around a Detached Breakwater

Abstract

A numerical model that combines a random wave transformation and a wave-induced current model was developed in order to predict the wave and current fields around a detached breakwater. The wave field was determined using the EBED model, as reported by Mase in 2001, with a modified energy dissipation term. The surface roller associated with wave breaking was modeled based on a modification of the equations in works by Dally and Brown, and Larson and Kraus, in which the term for the roller energy flux in the alongshore direction was added to the energy balance equation. The nearshore currents and water elevation were determined from the continuity equation together with the depth-averaged momentum equations. The model was validated by three unique high-quality data sets obtained during experiments on detached breakwaters in the large-scale sediment transport facility basin at the Coastal and Hydraulics Laboratory in Vicksburg, Miss. The calculated significant wave height and longshore current were in good agreement with these measurements, whereas the cross-shore current was underestimated because undertow processes were not included in the modeling (depth-averaged equations employed). The calculated wave setup was somewhat overestimated; however, the absolute differences between the calculations and measurements were overall relatively small.