Computational analyses of fully nonlinear interaction of an internal solitary wave and a free surface wave

Abstract

This paper is concerned with the interaction of an internal solitary wave (ISW) at the interface of two-layer fluid and the free surface wave on top of the upper layer. It is based on the potential flow theory since internal waves are associated with large Reynolds numbers. The potential flows in the upper layer and lower layer are modeled using a multi-domain boundary element method (MDBEM). The computational model is validated with the experimental results for the profile and speed of the internal wave. The MDBEM is suitable for the simulation of ISW in both small and large density jump stratified fluid system. The wave velocity is compared with the approximate analytical theory for various ratios of the fluid densities of the two layers. In addition, the amplitude, velocity and profile of the surface wave induced by ISWs are investigated. The free surface displacement is opposite to that of the interface, and the amplitude of the surface wave increases with the amplitude and density jump. The surface wave induced by an ISW can be soliton-like wave, propagating with the constant speed of the ISW and maintaining its profile.