Dispersive effects on wave-current interaction and vorticity transport in nearshore flows

Frequency dispersive effects on the interaction of waves and currents in a nearshore circulation system are analyzed. By means of both analytical and numerical calculations, we find that dispersive effects are important in the description of the correct amount of the wave forcing, represented, within the generalized-Lagrangian-mean-like approach, by the pseudomomentum $p$⁠. They are particularly important when describing the flow using depth-averaged velocities. For some configurations, the depth-averaged current is forced not only by the nondispersive terms but also, with the same intensity, by the dispersive forcing terms. In such terms is included a vortex-force dispersive contribution, usually negligible in a small-wave amplitude approximation, which arises because of the presence of dissipative terms.