Numerical study of cross-shore variations of bound super-harmonics over a single sandbar system

This study primarily investigates the capability of the one-dimensional mode of the SWASH model to reproduce bound super-harmonics resulted from self-coupling of the spectral peak. The model results were compared with an array of wave measurements along a straight perpendicular transect in west of Nowshahr Port in the Southern Caspian Sea. The wave model was calibrated during moderate conditions and the bispectral analysis was applied for model results and field measurements.It was revealed that the model can properly reproduce nonlinear waves experiencing significant shoaling as well as disappearing the couplings for breaking waves within stormy periods. Secondary and tertiary local peaks as results of self-coupling of the spectral peak could be found in the simulated wave spectra; however, erroneous intensive couplings were also represented by the model for very low energy conditions with no cross-shore wave transformation.The validated model results were used to investigate the variations of the bound triad interactions across the shore. It was found that the corresponding Ursell numbers for the most intensive positive couplings were in the range of 0.2-0.3. Also, it was concluded that the couplings may be drastically weakened before intensive wave breaking.

Automated summary

This study primarily investigates the capability of the one-dimensional mode of the SWASH model to reproduce bound super-harmonics resulted from self-coupling of the spectral peak. The model results were compared with wave measurements, and it was found that the model can properly reproduce nonlinear waves experiencing shoaling and breaking. The model also simulated secondary and tertiary local peaks as results of self-coupling.