# Forecasting of higher order spectral quantities of nonlinear random waves over surf zone

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## Abstract

Accurate modeling of energy dissipation mechanisms due to wave breaking in the frequency domain is an overdue task hampered by the facts that wave breaking is highly localized in time. On the other hand, a spatially localized eddy viscosity formulation based on the mixing length hypothesis is capable of providing accurate predictions of wave skewness and asymmetry in the surf zone. In this study, the structure of dissipation term is re-examined using the data of Kraus*et al.* (1992) and Buhr Hansen and Svendsen (1979) from the viewpoint of time dependent Boussinesq equations. Based on these results, the structure of frequency domain dissipation model over the surf zone is deduced. It turns out that dissipation due to wave breaking should be biased strongly toward higher frequencies in spectral calculations, and that a quadratic dependence on frequency within the dissipation coefficient comes closest to matching the desired structure of the breaking term. The prediction of skewness by numerical model with twenty harmonics involved is promising whereas the asymmetry in the surf zone is somewhat under-predicted.

## Keywords

skewness asymmetry surf zone nonlinear random waves wave breaking model## Preview

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