A nonlinear, non-dispersive energy balance for surfzone waves: infragravity wave dynamics on a sloping beach

A fully nonlinear non-dispersive energy balance for surfzone waves is derived based on the shallow water equations (NLSWE) to study nearshore dynamics of infragravity (IG) waves. Based simulations a relatively moderate and mild beach slope with non-hydrostatic wave-flow model (SWASH), new theory shows that spatial gradients in IG flux are nearly completely balanced by combined effect bottom stresses predominantly triad interactions. The confirms many features existing weakly theories, yields an improved description inner where become highly nonlinear. gain throughout shoaling outer surfzones driven interactions between pairs sea-swell (SS) decreased surfzone, primarily through cascade swell-band super-harmonic frequencies wave ultimately dissipated. Dissipation friction was weak both slopes. breaking, characterized triads three or two one SS wave, significant only deep inside slope. Even though broke slope, were responsible at least half net loss.