Effect of Asymmetric Directional Spreading on the Total Radiation Stress

Abstract

The process of wave refraction in nearshore zones can result in an asymmetric directional distribution of spectral energy when oblique, multi-directional wave fields propagate into shallow water areas. Here the effect of this directional asymmetry on the net wave-induced radiation stresses is analyzed. The net radiation stresses are calculated for a shoaled JONSWAP frequency spectrum with both symmetric and asymmetric directional distributions and then compared with those calculated from the commonly-used monochromatic formulation (appropriate for spectra that are narrow-banded in frequency and directions). Past studies have demonstrated that the use of the monochromatic approximation in radiation stress calculations results in a significant overestimation of the radiation stress components