NUMERICAL MODELLING OF THREE-DIMENSIONAL WAVE-DRIVEN CURRENTS IN SURF-ZON

The numerical modelling of time-averaged three-dimensional currents due to breaking waves is presented. The basic equations and the closures are described. The driving terms in the momentum equations are the radiation stresses derived from "organised" velocity of waves and the roller contribution. The model is validated on measurements collected in a flume. The application to the case of a rectilinear beach with oblique incidence wave displays a helicoidal circulation. In the situation of a detached breakwater with a normal wave, depth-integrated currents show two large symmetrical cells in the lee of the structure whereas streamlines near the bottom converge spirally toward the centres of the eddies.