3D Hydrodynamic Model With The Depth-Dependent Radiation Stresses

With the development of computer technology, three dimensional hydrodynamic model is becoming more and more widely used. In order to simulate the nearshore current reasonably, all dynamic factors should be included in the model. So it is of great importance to solve the engineering problem in esturine and coastal area to establish the 3D numerical hydrodynamic model that takes into account the depth-dependent radiation stresses.In this thesis, expressions for depth-dependent radiation stresses are introduced on the basis of linear wave theory, and then the radiation stresses from the deep water to the shallow water is discussed. At last different radiation stresses expressions are compared. The results show that the radiation stresses in deep water decrease from the water surface to bottom in parabolic shape, while the radiation stresses in shallow water decrease linearly from the water surface to bottom, and the radiation stresses in the intermediate water are transitional. However, the conventional two dimensional radiation stresses fail to reflect this phenomenon. Comparisons show that the different formulae of three dimensional radiation stresses are basically consistent with each other.By adding the depth-dependent radiation stresses to the ELCIRC three dimensional flow model, the wave set-up, set-down and undertow are studied. The simulated results are compared with the experimental data. Wave field used for the computation of radiation stresses is provided by the REF/DIF wave model based on the parabolic mild-slope equation. The numerical results of the model agree with the experimental data satisfactorily. It shows that the three dimensional flow model with the depth-dependent radiation stresses can simulate the hydrodynamic phenomenon of nearshore area reasonably.