双丁坝间流场及局部冲刷的数值模拟研究

Study on Numerical Simulation of Flow Field and Local Scour between Double Spur Dikes

因双丁坝对河道流场及泥沙冲淤的影响有别于单丁坝,选取实际河道丁坝群中的双丁坝建立三维模型,并拟定5种对比方案,基于计算流体力学(CFD)数值模拟的方法,采用RNG k-ε模型和VOF法捕捉液体自由面进行模拟计算,对比分析了双丁坝协同工作时的水沙运动特性。流速与冲刷深度计算结果表明,当双丁坝长度相差大于10 m时,易形成不均匀的河道流场,不利于河势控制;当首、次丁坝长度协调时,冲刷坑尺寸较小,坝间河岸被双丁坝回流区掩护,近岸流速较小,河道流场均匀,对丁坝稳定、河道治理与河势控制效果较好。

Because the effect of the double spur dikes on river flow field and sediment erosion and sedimentation are different from single spur dike,the double spur dikes in the spur dike group in actual channel are selected to establish a three-dimensional model,and five comparison schemes are proposed.Based on the computational fluid dynamics(CFD)numerical simulation method,the RNG k-εmodel and VOF method are used to capture the free surface of water for simulation calculation,and the water and sand movement characteristics during the cooperative action of double spur dikes are comparatively analyzed.The calculation results of flow velocity and scour depth show that,(a)when the length difference of the double spur dike is greater than 10 m,it is easy to form an uneven river flow field,which is not conducive to river regime control;and(b)when the lengths of the first and second spur dike are coordinated,the size of the scour pit is smaller,the riverbanks between the dikes are covered by the return area of double spur dikes,the near-shore velocity is smaller,and the river flow field is uniform,which is beneficial to the stability of spur dikes and the treatment and control of river.