基于自适应网格的急流条件下污染物输运高效高精度模拟

为了高效准确模拟急流条件下突发水污染事件中污染物的输运规律,基于自适应网格技术构建了Godunov格式有限体积模型。模型利用自适应结构网格离散二维浅水控制方程,对水位梯度或污染物浓度梯度较大的区域进行精细网格划分,同时细化干湿边界区域网格。模型采用MUSCL-Hancock方法求解二维浅水控制方程,使模型具有时空二阶精度;利用HLLC格式近似Riemann解计算界面通量,对界面两侧的Riemann变量进行非负重构和局部底部高程修正以确保模型计算的和谐性和稳定性。算例验证表明:自适应网格技术可以自动识别水位梯度或污染物浓度梯度较大的区域以及干湿边界区域并细化该区域网格,保证模型模拟精度的基础上,提升模型模拟效率;该模型能够准确高效地模拟急流条件下污染物的输运过程,适用于突发水污染事件的评估、预警和应急管理。

High efficient and accurate simulation of pollutant transport in torrential flow based on adaptive grid method

A Godunov-type scheme finite volume model based on adaptive structured grid method is pro-posed for accurately simulating pollutant transport in sudden water pollution accidents with torrential flow conditions.In the model,two-dimensional shallow water governing equations are discretized by adaptive structured grids.The structured grids with high gradients of water level or pollutant concentration are subdi-vided to improve grid resolution.In addition,the grids near wet/dry fronts are also subdivided.The model has spatial-temporal second-order precision through solving shallow water governing equations by MUS-CL-Hancock method.HLLC''s approximate Riemann solution is used to compute the interface flux based on non-negative reconstruction and local modification of bed slope,it can maintain the stability and well-bal-anced condition of the model.The test results indicate that adaptive gird method can automatically identify and subdivide the grids with high gradients of water level or pollutant concentration as well as the girds near wet/dry fronts.It can improve model computational efficiency without compromising solution accuracy.The model can efficiently and accurately simulate pollutant transport in sudden water pollution accidents with torrential flow conditions and is applicable for assessment,early warning and emergency management of sudden water pollution accidents.