NUMERICAL MODEL FOR FOCUSED WAVE TRANSFORMATION OVER A SUBMERGED BAR

A numerical wave model is established by a set of fully nonlinear Boussinesq equations with enhanced dispersion relationship. This model is verified by experimental data of the evolution of focused wave groups at uniform depth. Then, the model is used to study the propagation of focusing wave groups over a submerged bar. The results indicate that: in the shoaling region, the wave crests become more and more peaky and the troughs become more and more broaden with the decrease of water depth. The associated amplitude spectra indicate that there is significant increase energy at higher- and sub-harmonics. However, in the region of the top of a bar and the de-shoaling region, the wave packet shape gradually evolves from a wave groups to a nearly sinusoidal shape wave train. The phenomenon of inverse of energy transfer is also observed in this region. Furthermore, it is observed that: in the frequency region of primary waves, the energy of frequency components at the adjacent of peak frequency increases in the de-shoaling region, that is, the peakiness of spectrum shape decreases.