桩墩影响下的水动力数值模拟

Numerical simulation of open channel flow influenced by pile piers

建立平面二维数值水槽模型,将桩墩作为不透水边界处理,利用三角形加密网格精确模拟桩墩形状,计算分析缓流河道中单排桩墩影响下水位和流速的变化,并探讨了方墩与圆墩对水流变化的影响差异以及糙率与紊动黏性系数对壅水数值的敏感性。研究结果表明:①桩墩引起的水流变化沿纵、横向呈现出不同的分布形式,沿横向呈波状分布。墩身上游主要表现为水位壅高,流速减小;墩身下游则表现为水位跌落,流速在墩间区域增加,而在墩后区域减小。②方墩对水流变化的影响比圆墩大;上游壅水随糙率变化较小,但对紊动黏性系数的变化较为敏感。

A 2-D numerical model for open channel flow influenced by pile piers is set up, considering the piers as impermeable area. The method of gradually refined triangular meshes is used to simulate the shape of piles with high precision. Based on this model, the water level and velocity of water flow, which are influenced by single line piers, are calculated, and the differences in the influence of square piles and circular piles on water flow are discussed. Furthermore, the effect of Manning＇ s roughness and eddy viscosity on the upstream backwater is analyzed. The result shows that the variation of water level and velocity caused by piles are different along the vertical-section and cross-section, and the variation of water level presents a ＂wave-like＂ distribution along the cross-section. In general, the water level rises and the velocity decreases in the upper reaches, while in the lower reaches the water level fal.ls and the velocity increases. It can also be concluded that square piers have greater influence on water flow than circular ones, and the backwater upstream is mere sensitive to the eddy viscosity than to the Manning＇s roughness.