Kinetic equations in a third-generation spectral wave model

Abstract

The Hasselmann kinetic equation (HKE) forms the cornerstone of present-day spectral wave models. It describes the redistribution of energy over the wave spectrum as a result of resonant four-wave interactions, and theoretically prescribes wave evolution on a slow time scale, where and are typical wave steepness and frequency. Alternatives to the HKE (e.g. the generalized kinetic equation (GKE)), including the effects of non-resonant four-wave interactions, are believed capable of evolving wave fields on a fast time scale. It is beyond doubt that these alternatives could reasonably predict changes of unidirectional waves whereas the HKE cannot. For angular spread wave fields, however, it is s..