Numerical Simulation Of Ocean Internal Waves And Surface Waves

Ocean internal waves and surface waves are the two main factors of influencing the ocean fluctuating. They are closely related to the human production and daily lives; they also seriously influence the oceanic environment, coastal protection, ocean and coastal engineering, fishing production, military and navigation. The contents of the dissertation consist of the following two aspects.Part one deals with the numerical simulation of ocean internal waves. Based on Euler equations, the finite volume method is employed to develop a numerical model for internal wave propagation in continuously stratified ocean with variable water depth. In the model, the advection terms are discretized with the Total Variation Diminishing (TVD) scheme, and the SIMPLE algorithm is introduced in the present numerical model. Further, in order to simplify the calculation process and easily adapt different TVD schemes, the SIMPLE algorithm is modified. The open boundary at the far end is treated using a sponge layer combined with the sommerfield radiation condition. The numerical results with constant depth are compared to the analytical solutions and good agreements are found. The characteristics of internal wave propagation are analyzed. Numerical simulations are undertaken for the calculation domain with a submerged dike as well as the internal waves'generation and propagation process induced by density perturbations. It is shown that the present numerical model can effectively simulate the propagation of internal waves.Part two deals with the numerical simulation of ocean surface waves. Based on the CCMP remotely-sensed sea wind fields, wind wave fields near the estuary of Pearl River are simulated with SWAN nested in WAVEWATCH. The numerical results of ten months'significant wave heights, wave periods and wave directions are compared to the measured data quantitatively, respectively. It is indicated that for significant wave heights, the mean absolute error is 15.4cm, SI(Scatter Index)is 0.240 and the correlation coefficient is 0.925; for wave periods, the mean absolute error is 1.9s, SI is 0.433 and the correlation coefficient is 0.636; for wave directions the mean absolute error is 23.9°.The numerical results are in agreement with the measured wave heights and wave directions .However, due to the drawback of the third generation wave models, the calculated wave periods are smaller than the measured ones. Generally, the numerical model of this paper can simulate the wave fields near the estuary of Pearl River effectively. Typhoon waves in 2006 were simulated using CCMP wind fields, modeled wind fields and the superposition of the two wind fields, respectively. Influences of different winds on typhoon waves were preliminarily discussed.