Nonhydrostatic Modeling of Nonlinear Deep-Water Wave Groups

Abstract

A nonhydrostatic model with a higher-order top-layer pressure treatment is developed. Accuracy with respect to linear wave dispersion and wave nonlinearity is carefully examined. The model is thereafter applied to simulate nonlinear deep-water wave groups. For slowly modulated wave groups, the model well predicts the characteristics of bichromatic waves better than those obtained by the fourth-order nonlinear Schrödinger equation and the multilayer Boussinesq model. For fast evolution of focusing wave groups, the model accurately captures the limiting extreme wave conditions. Particularly the predicted local wave steepness of a narrow-banded wave group is higher than that of a broad-banded wave group, supporting the importance of spectral bandwidth in determining the limiting wave condition in the previous study. Overall, the agreement between the model’s results and experimental data are excellent, demonstrating the capability of the model on resolving wave-wave interactions in the nonlinear deep-water wave groups.