Development Of Two-dimensional Numerical Model Of Sediment Transport And Topographic Evolution Based On Quadrature-free Nodal Discontinuous Galerkin Method

Sediment transport and topographic evolution is an important topic in estuarine and coastal studies.In order to reasonably simulate the sediment transport in the process of topographic change,a two-dimensional numerical model of sediment transport under combined action of waves and current is developed based on the quadrature-free nodal discontinuous Galerkin method.The main research work in this paper is as follows.Firstly,the current research achievements of two-dimensional numerical model of sediment transport under combined waves and current are reviewed.The reference concentration method and equilibrium concentration method are selected as the source terms of convection-diffusion equation.The model governing equation is discretized by the quadrature-free nodal discontinuous Galerkin method in space.And the off-line wave-current coupling is realized by SWAN model.The sediment transport and topographic evolution are solved after off-line wave-current coupling.Then,different experiments are used to verify the model.An ideal convectiondiffusion example shows that the model can solve the convection-diffusion equation effectively and reach the optimal convergence with the order of O(p+1).The example of suspended sediment shows that the model can effectively simulate the suspended sediment transport processes.The example of sand wave evolution proves that the model can accurately simulate the process of bed evolution.A dam-break example on a movable bed shows that the model can reasonably simulate the rapid topographic evolution caused by complex flow and sediment erosion and deposition.A channel migration example with sediment bed in flume shows that the model can effectively simulate the long-term sediment movement and topographic evolution under waves and current.Finally,the model is applied to the simulation of sediment motion in Hongtang Bay,Sanya.The sediment transport in the sea area under tidal current is simulated,and the results compared with the measured values at the observation stations.Through the analysis of the simulation results under tidal current and waves,the effects of waves in different recurrence periods on the flow field and sediment concentration in the sea area are discussed.The model reasonably simulates the tidal current,waves and sediment motion around Hongtang Bay,which provides an effective basis for engineering construction near Hongtang Bay in Sanya.