Numerical Simulation Of Wave, Wave-induced Current And Sediment Transport In Complex Coastal Zone

Sediment transport is one of the most active phenomenon under nearshore wave and currents in coastal area.The researches in nearshore process of the hydrodynamics and sediment transport are especially important as the development of offshore engineering, resource exploitation and marine traffic et al. Sediment transport is the cause of coastal evolution, channel siltation and can undermine the root of constructions, and it is the key reference of the nearshore engineering such as the port design, the channel arrangement and the layout of breakwater. Therefor, the study of nearshore waves, wave-induced longshore current and sediment transport has a good reference value to nearshore engineering and it is very important to predict coastal evolution.The numerical model included the nearshore wave propagation model, wave-induced currents model and sediment transport model, was established under a automatic quad-tree grid system. Compared with the uniformed grid, quad-tree grid has good flexibility for complex numerical zone and boundary, especially for complicated hydrodynamics. Compared with the the general unstructured grid, there is no need to introduce shape function for quad-tree grid in the process of dispersing numerical model and avoid to bring in intricate cross term. The automatic quad-tree grid system adopted in this paper could subdivide grid automatically according to the relation of the wavelength or water depth and the size of grid. Compared with the existing numerical models, this grid system can save a large number of memory space and computation time. Under this grid system, the numerical model was dispersed by using the finite volume method.The elliptic mild-slope equation considering effect of the broken item was used to simulate the wave propagation of Hazaki coastal to verify its validity. The depth-averaged two-dimensional shallow water equations was applied to the Hamilton and Ebersole experiments and A.J.H.Reniers* and J.A.Battjes experiments to simulate the wave-induced longshore current, and analyzed its applicability to complex coastal zone by comparing the numerical results with the experiment data.The nearshore sediment transport model included suspended sediment diffusion equation and bed load equation based on the nearshore waves and wave-induced longshore current. The model was applied to the LSTF experiments and the field measurement data surveyed by Miller to certify its validity and applicability for different geography and incident conditions. The model verification results showed that the wave propagation numerical model, the wave-induced longshore current model and the nearshore sediment transport model could apply to complex coastal zone preferable.