三维水动力泥沙输移模型及其在珠江口的应用

为研究河口的泥沙输移规律和最大浑浊带与盐水入侵、咸淡水混合等的关系，本文提出了具有二阶精度、建立在9结点有限单元上的三维水动力及泥沙输移模型，该模型考虑了由水平密度梯度引起的斜压项、引用2．5阶Mellor-Yamada紊流模型耦合计算水流的涡动黏滞性系数与物质的紊动扩散系数。本模型采用破开算子法求解控制方程：用欧拉-拉格朗日法求解水平对流项；用有限元法求解水平扩散项；有限差分法求解垂向扩散项。模型应用于模拟珠江口的泥沙运动，计算域包括整个河口的八大口门，用1998年7月的洪季大潮实测资料进行了潮位、流速及流向、盐度及含沙量等的验证，模型计算结果与实测结果吻合良好。在模型验证的基础上，文中简要讨论了珠江河口的泥沙输移、盐水入侵及最大浑浊带等物理现象。

Three-dimensional modelling of sediment transport in the Pearl River Estuary

A three-dimensional baroclinic model of 9-node quadrilateral elements with second order accuracy for hydrodynamics and cohesive sediment transport is introduced in this paper.The operator-splitting scheme is used to solve the governing equations: using the Eulerian-Lagrangian method for solving the horizontal advection terms;using the finite element method for horizontal diffusion terms;using the finite difference method for vertical diffusion terms.The Mellor-Yamada level 2.5 turbulence closure sub-model is coupled to get more reasonable vertical eddy viscosity and substance turbulence diffusion coefficient.The model was applied to simulate a 3-D suspended sediment transport in the Pearl River Estuary with a spring tide and a neap tide in wet season(July 1998).The computational domain of the simulation covers all the 8 outlets of the Pearl River.The model is validated with field data in terms of tidal levels,tidal flows,salinities and suspended sediment concentrations.The numerical results are in good agreement with the field data.In addition,based on the simulation results,some physical phenomena,such as salinity intrusion,maximum turbidity in the Pearl River Estuary are discussed briefly.