AN IMPLICIT 2-D DEPTH-AVERAGED FINITE-VOLUME MODEL OF FLOW AND SEDIMENT TRANSPORT IN COASTAL WATERS

Abstract

An implicit depth-averaged 2-D finite volume model has been developed to simulate sediment transport and bed morphological changes under actions of currents and waves near coastal inlets. The model computes the depth-averaged 2-D shallow water flow and non-equilibrium transport of total-load sediment, accounting for the effects of wave radiation stresses and turbulent diffusion induced by currents, waves and wave breaking. The model uses a quadtree rectangular mesh to locally refine the mesh around structures of interest or where the topography and/or flow properties change rapidly. The grid nodes are numbered by means of an unstructured index system for more flexibility of mesh generation. The SIMPLEC algorithm is used to handle the coupling of water level and velocity and the Rhie and Chow's (1983) momentum interpolation method is adopted to determine the intercell fluxes on non-staggered grid. Well-developed longshore current and wave setup determined with the reduced 1-D momentum equations are used as the cross-shore boundary conditions. The model has been tested in several laboratory and field cases, showing good performance. In particular, it can use a long time step and is efficient in computation on a PC platform. It has a potential for simulation of long-term coastal morphodynamic processes.