High-level Green–Naghdi wave models for nonlinear wave transformation in three dimensions

The Green–Naghdi (GN) wave models are categorized into different levels based on the assumptions made for the velocity field. The low-level GN model (Level I GN model or called the GN-1 model) is a weakly dispersive, strongly nonlinear wave model. As the level goes up, the high-level GN model becomes a strongly dispersive, strongly nonlinear wave model. This paper introduces the algorithm to solve the Green–Naghdi wave models of different levels in three dimensions. The high-level GN (GN-3 and GN-4) models are applied to three-dimensional wave problems for the first time. Three test cases are considered here. First one is on the wave evolution in a closed basin. The symmetry, in the xx and yy directions in this case, verifies that the algorithm introduced here works well. The GN-3 results are also compared with the linear analytical results for a small wave elevation in a closed basin, and the agreement is good. The last two cases involve wave diffraction problems caused by an uneven seabed. In both of the last two cases, the GN-3 model is proved to be the converged GN model. The agreement between the GN-3 model and the experimental data and numerical predictions of the fully nonlinear Boussinesq model of others is also very good.