Detection and analysis of coherent groups in three-dimensional fully-nonlinear potential wave fields

• Published in: Ocean modelling (Oxford) 2016-07, Vol.103, p.73-86
• Main Authors: Sanina, E.V., Suslov, S.A., Chalikov, D., Babanin, A.V.
• Format: Article
• Language: English
• Subjects: Coherent wave groups; Dynamic tests; Extreme values; Laplace equation; Marine; Mathematical models; Nonlinear waves; Ocean models; Oceans; Statistics; Three dimensional; Velocity of groups
• ISSN: 1463-5003; 1463-5011
• DOI: 10.1016/j.ocemod.2015.09.012

•A method to define and detect the groups in three-dimensional nonlinear wave fields is suggested.•Quasi-1D wave groups are found to exist over time spans of 1.5–4 wave periods.•Mean speed of group propagation is found to be constant 0.7 of the phase speed of spectral peak. 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 nθ, 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 velocity potential subject to nonlinear kinematic and dynamic boundary conditions at the free surface. The main characteristics of wave groups such as their average velocity, maximum group wave height, lifetime and length are analysed. The statistics of extreme waves occurring in the detected groups are discussed. Spatial and temporal scale characteristics of wave groups are compared to the previous results.