Parameterization of asymmetries for obliquely incident waves in coastal region

In the coastal region, the characteristics of wave asymmetry are closely related to the sediment transport. It plays a crucial role in determining the structure failure of a coastal defense due to the toe scour. However, most of the researches related to the wave asymmetry focus on the normal incident waves, there have not been sufficient researches on the evolution of wave asymmetry for obliquely incident waves. Therefore, it is necessary to investigate the evolutions of wave asymmetries for obliquely incident waves in the coastal region. In this study, a numerical model is developed to conduct the numerical experiments, which is based on the fully nonlinear Boussinesq equations. Irregular waves with incident angles ranging from 0° to 75åre simulated. The effect of incident angle on the wave asymmetries is analyzed by comparing the numerical results obtained with different incident angels. The results showed that the parameters of wave skewness and asymmetry, as well as bispectrum in the shoaling process, are moderated with an increase in the incident angle. This indicates that the degree of the triad wave interactions could be weakened by increasing the incident angle, which leads to a decrease in the nonlinear wave characteristics. In conclusion, the empirical formulae for wave skewness and wave asymmetry by combining the influence of incident angles are recommended.