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 and in broad-banded seas. The present results show that the inclusion of directional asymmetry in radiation stress calculations reduces this overestimation for but increases the overestimation for for a range of dominant wave directions. Thus, directional asymmetry is an additional factor that contributes to overestimation when the monochromatic approximation is used for and can therefore also lead to an overestimation of associated parameters such as alongshore current velocities and alongshore sediment transport rates.
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Published In
Journal of Waterway, Port, Coastal, and Ocean Engineering
Volume 141 • Issue 6 • November 2015
Copyright
© 2015 American Society of Civil Engineers.
History
Received: Oct 2, 2014
Accepted: Feb 6, 2015
Published online: Jun 10, 2015
Published in print: Nov 1, 2015
Discussion open until: Nov 10, 2015
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