长江口北支基于混合网格的通量差分裂水流水质计算模式

本文建立了基于三角形四边形混合网格的二维水流水质耦合数值计算模式。网格通过推进阵面法自动生成，控制方程采用有限体积法对守恒变量进行离散，应用通量差分裂格式(FDS)计算边界上的水量、动量和污染物法向数值通量。模型应用于长江口北支崇海公路大桥修建后的流场浓度场的数值模拟。网格根据工程实际需要分区布置．在工程外区域采用有结构的四边形网格布置，既可贴合实际岸线边界，又便于组织数据结构；在工程附近区域采用无结构的三角形网格布置，利用三角形网格的灵活性实现复杂地形边界和局部小尺度流场浓度场的精细模拟。模型计算出的流场和浓度场与实测值对比令人满意，较好地解决了复杂边界和工程网格尺度问题。

Numerical simulation of flow and pollutants in the north branch of Changjiang estuary by hybrid grids flux difference splitting scheme

Based on the triangle-quadrangle-hybrid meshes, a 2D flow-pollutants coupled numerical model is established. The unstructured grids are generated by the advancing front method. By use of the finite volume method, conservative variables in the governing equations are discretized, and the normal flux through boundaries is calculated by flux difference splitting scheme. The model is applied to simulate the flow and concentration fields in the north branch of Changjiang estuary after the building of Chonghai Road Bridge. The grids are distributed according to demand of the actual project in different research areas. Structured quadrangular grids are distributed in areas far from the project and unstructured triangular grids are distributed in areas close to the project. The calculated values of flow and concentration fields and observed data are in good agreement, therefore, the model has basically solved the difficulty of complex boundaries and the grid magnitude is fit for the project in numerical simulation.