Numerical simulation of surf-swash zone motions and turbulent flow

A two-dimensional numerical model was presented for the simulation of wave breaking, runup and turbulence in the surf and swash zones. The main components of the model are the Reynolds-Averaged Navier-Stokes equations describing the average motion of a turbulent flow, a k-epsilon turbulence closure model describing the transformation and dissipation processes of turbulence and a Volume-Of-Fluid technique for tracking the free surface motion. Nearshore wave evolution on a sloping bed, the velocity field and other wave characteristics were investigated. First, the results of the model were compared with experimental results for different surf zone hydrodynamic conditions. Spilling and plunging breakers were simulated and the numerical model investigated for different wave parameters. Besides the flow field, the turbulence field was also considered and the spatial and time-dependent variations of turbulence parameters were discussed. In the next stage of the study, the results of numerical experiments were compared against two sets of experimental data in the swash zone. Generally, there is good agreement between the results of the model and experimental data, except for turbulence predictions near the breaking point. On the other hand, turbulence predictions were found to be excellent for the swash zone. The model pro-vides a precise and efficient tool for the simulation of the flow field and wave transformations in the nearshore, especially in the swash zone. The numerical model can efficiently simulate the sur-face elevation of the vertical shoreline excursion on sloping beaches, while swash-swash interac-tions within the swash zone are accounted for.