| According to the two aspects of ocean wave studies that I have made as a P.H.D candidate, the dissertation is divided into two parts: Part I is the development and Applications of a 2-D numerical wave tank(NWT) and Part II the study of wave-current interaction.In Part I, based on the systematic review of the study history and prospect of NWT, the detailed process of a 2-D NWT model developed independently is reported.The two key discretization methods, boundary element method (BEM) and mixed Eular-Langurange (MEL)method, are introduced in detail, and an integrated flow chart of the detailed time-domain simulation steps of NWT is presented. Subsequently, the special numerical techniques including the wave generation and absorption that are used in the model is illuminated. Moreover, a spindly shaped damping zone is designed to improve the absorption capability of conditional damping zone, which has the function of two directional wave absorption and low-pass filtering. Combining with a piston wave absorber, the wave absorption efficiency is proved to be powerful.A series of testing experiments are made to check the performance of the model, including the simulations of a stationary wave and a plunging wave rush on the slope beach. In particular, a group of ISOPE official benchmarks are run so as to compare the developed NWT with others. The results show that the model has perfect functions of wave generation and absorption and is stable and accurate enough for simulating fully nonlinear waves exactly. That is to say, the model can meet the actual demand of common numerical experiments very well.Several experiments with the developed NWT are carried out to prove its practicability and potential capability, through which it is expected that the developed NWT would find its application in the research on the process of ocean mixing. In the first experiment, a feasible scheme of simulating interfacial wave is presented by coupling two models with each other to simulate some interfacial wave phenomena. The simulating results indicate that the scheme is stable in linear frame, and exists weak instability on the intersecting points of lateral boundary and interface in nonlinear frame. In present stage, a technique of using damping zone to limit the movement of the intersecting points is used to avoid this instability problem, however, to solve it thoroughly, the original model has to be modified in the future.In the second experiment, the topography stirred waves in a to-and-fro current is simulated, in which the rough relationship of the stirred waves and the topography is made out, a phenomenon of high frequency instability and breaking of surface on curtain condition is detected and analyzed.In Part II, based on some researches that I have made as an assistant of my tutor, the present advance of international research of wave-current interaction is review systematically. Subsequently, the waves induced forces and their driven effects on currents are studied in detail.In the discussion of the effects of currents on waves, according to the wave radiation theory and the law of wave action conservation, the equivalence of none vorticity condition of the vector of wave number in constant wave field and Fermat Theory istestified. The dynamic and kinematics effects of background currents on waves are introduced concisely. The effect of the change of surface elevation on the wave development and elimination is pointed out for the first time, which provides the necessary theoretical basis for the development of united current-wave-tide model; hi the discussion of the effects of waves on currents, a variety of wave-induced forces on the geostrophic and viscous condition and their producing mechanism are introduced systematically, their corresponding wave-induced currents are also analyzed qualitatively. Moreover, a complete expression of wave-induced Reynolds stresses tensor is presented for the first time.In succession, to amend the preceding studies, a genuine geostrophic small amplitude wave so...
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