Numerical study of the characteristics of wave–wave interactions in a multiphase wave field

This paper presents a numerical study of wave–wave interactions in multiphase wave fields using the boundary element method (BEM). Variations in wave height distributions, spatial velocities, and particle trajectories in multi-component wave generation were investigated using a 2D numerical wave tank, which models the interaction between an incoming wave and a reflected wave. This study examined wave–wave interactions in various wave cases, and explored the interactions and variations of velocity fields in various wave periods, in particular, waves with greater discrepancies. Surf beats in the surf zone are the main cause of the cross-shore motion, and induce the generation of high-frequency energy, which is transferred to high-frequency harmonic waves. This study modeled oscillations caused by surf beats and back swash, generated by high-frequency, multi-phase reflected waves, to investigate the deformation of wave profiles, velocity fields, and the movement of particle path-lines. The results revealed that incident waves are affected by high-frequency reversed waves that propagate against them from the other side of the flume, reducing average wave height in the whole area, but become less affected with increasing diversity between the two wave frequencies and/or wave height.