Statistics of coherent groups in three-dimensional fully-nonlinear potential waves

Abstract

We investigate the emergence of coherent groups in three-dimensional fully-nonlinear potential deep water waves whose initial spectrum is assumed to be of the JONSWAP type with directional distribution given by (cos θ)n, where n is the integer varying from 1 to 16. The analysis is based on the results of long-term wave simulations performed using a numerical solution of a three-dimensional Laplace equation for the potential with nonlinear boundary conditions. The main characteristics of the wave groups such as average group velocity and maximum group wave height are analysed. The statistics of extreme wave occurrence in the groups are discussed.