光滑及粗糙明槽湍流流动大涡模拟

Large Eddy Simulation of Turbulent Flows in Smooth a nd Rough Open Channels

采用大涡模拟 (L arge Eddy Simulation)方法和 Smagorinsky亚格子模型数值计算了光滑及粗糙明槽湍流运动。以槽高为参考长度的雷诺数分别为 30 0 0 ,2 2 80 0和 10 5,数值离散方法为有限体积法 ,自由面的处理使用了简单了刚盖假定 ,固壁面采用了壁函数。与低雷诺数直接模拟 (Direct Simulation)和物理实验结果相比 ,本文数模呈现了良好的预测效果 ,估计的湍流宏尺度 (Macroscale of Turbulence)证实了固壁附近台劳假设的局限性。

In this paper, the turbulent flows in smooth and rough open channels are studied by the large eddy simulation meth od combined with the Smagorinsky subgrid scale model. The Reynolds numbers based on the bulk velocity and depth of channels are selected as 3000, 22800 and 10 -5 respectively. The numerical algorithm is the finite volume method. The rigi d lid assumption is used for the free surface, and the wall function for the sol id wall. Good results are achieved in this prediction by comparison with the dir ect numerical simulation at low Reynolds number and physical experiments. The es timated macroscale of turbulence by the large eddy simulation reveals the limita tion of the Taylor hypothesis near the wall.