Fluid acceleration in the swash zone

A Navier-Stokes solver (NEWFLUME) is used to evaluate velocity, local, convective and total accelerations in the swash zone for three different types of breaking, surging, plunging and nearly spilling waves which are obtained by altering the beach slope holding the forcing conditions constant. The hydrodynamic results have been presented for a level right above the bed which is more important for sediment transport issues regarding the three breakers. Also, depth-averaged velocity and acceleration parameters are shown. The results show that regardless of the breaker types, moving from the inner surf to swash zone, the flow velocities magnitude increases and the largest onshore-directed velocity occurs at the beginning of uprush, also the greatest offshore velocities take place at the end of backwash phase. It has been found that the convective accelerations are mainly onshore-directed or nearly zero and reach their highest values at the early uprush and at the end of backwash phases in the onshore direction. We also find that in the surging case the local accelerations are offshore-directed during a swash event except at the beginning of swash cycle when the local acceleration value decreases during the time and reaches its maximum offshore-directed value at the mid-swash time. Just outside and at the seaward edge of the swash zone, local accelerations are shoreward-directed for the plunging case and near zero but shoreward-directed for the spilling wave.