丁坝群附近流场及局部冲刷的三维数值模拟

3D numerical simulation of flow field and local scour around spur dikes

为探索丁坝群附近水流流场,揭示其局部冲刷的形成机理,该文采用Flow-3d软件,选取RNG k-ε湍流模型和以希尔兹(Shields)数为基础的泥沙推移质输沙率模型对上挑丁坝群的周围流场分布和局部冲刷进行了三维数值模拟。研究发现,丁坝群间涡系结构复杂,第一座丁坝坝头处有一对反向的旋涡和下潜水流,切应力达到最大值,使得该位置有较大冲刷坑发生,解释了冲刷机理。冲刷坑的模拟深度和范围与实验结果吻合较好,表明该模型可以用于丁坝群及相关河道整治工程的流场和冲刷坑计算。

To reveal the mechanism of flow field and local scour around spur dikes, the present paper uses FLOW-3D software to simulate the three-dimensional flow and local scour around upward slopping spur dikes. Selected turbulence model is RNG κ- εmodel and the bed-load transport model is based on Shields number. Numerical simulation results show that the vortex is so complex between dikes. The bigger scour hole occurs in the first head of dike due to the combined effect of reverse vortexes, submerged flow and maximum shear stress. It also explains the scour mechanism. Obtained depth and scope of scour pit around spur dikes coincide well with experiment. It shows that the model can be applied to the calculation of flow field and scour pit around spur dikes and related river regulation engineering.