Boussinesq Modeling Of Wave-Current Interaction In The Nearshore Zone

Water waves and currents usually coexist, in the nearshore zone. The flow has a great influence on the wave deformation and energy transfer. For example the Doppler effect, the following currents increase wavelengths and decrease wave height, while the opposing currents decrease wavelengths and increase wave height. Meanwhile the wave and current interaction will have influence on sediment movement and ship navigation. Therefore, the engineers and scientists pay more and more attention to the research of wave-current interaction. Because the water depth of the nearshore is shallow and the wave nonlinearity is strong, the enhanced Boussinesq model is an ideal model to do the research on the nearshore wave-current interaction.This thesis adopts a set of fully nonlinear Boussinesq equations with the accuracy of dispersion relation up to the order of Pade[4,4] to simulate the evolution process of wave current interaction over the submerged sills with uniform steady currents. In order to mitigate the wave reflection at the open boundaries, the waves are generated inside the computational domain and the sponge layer is used. The data of experiments of Luth and Dong et al. were used to verify the accuracy and feasibility of the numerical model.Wave reflection, refraction and diffraction may occur around the structures. In this thesis, a time-domain separation method using time series measured from multiple measuring points to separate higher-order harmonics, and the method of least squares is applied to reduce errors which caused by the measuring and etc.The results were compared and analyzed to be good. The process of wave evolution over the submerged dike is complex. The energy transfer occurs between the various orders of harmonics, the free and bound harmonics of the same order. The flow affects the energy transfer between them. This thesis discusses the high-order harmonics with varying flow velocities and low-frequency generated by bichromatic waves over a submerged breakwater and summarizes the impact of the flow on waves propagating over the submerged dike.