明渠条件下单丁坝绕流特征的数值模拟

Numerical simulations of flows around a single spur dike in an open channel

丁坝结构广泛应用于水利工程中,用以调整水流和护滩固堤,维护优良的水道通航条件。针对单丁坝局部水流,基于非结构网格,采用有限体积法(FVM),建立了三维自由表面水流模型,湍流模型采用S-A一方程模型。针对非淹没、正挑单丁坝,开展了系列Fr数条件下的水流模拟。重点分析丁坝局部流动结构,探讨丁坝坝根处局部涡系演化等特征,研究了丁坝下游回流区长度和宽度的变化,总结了丁坝引起的剪切流的沿程变化特征。

Spur dike structures are widely used in hydraulic engineering, by constructing series of spur dikes perpendicular to the river banks the flow is kept away from the erodible banks,and as a result the laterally confined flow is accelerated to a sufficiently high velocity to keep the navigation channel at the proper depth. This paper is focused on with flows around a spur dike. We established a 3D model with free surface,which is based on unstructured meshes. The finite volume method （FVM） is employed to discretize the governing equations and one equation S-A turbulence model was used to simulate the turbulent flow. For study cases with different Fr number,we analyzed the flow structures near the non- submerged spur dike,discussed the formation of the vortex system at the base of the spur dike. Furtherly the length and width of the recirculation zone were calculated to reveal the evolution of the shear flow generated from the spur dike tip.