后台阶下游水流泥沙运动模拟研究

Simulation of fluid-sediment particle motion at the downstream of backward-facing step flow

利用计算流体力学软件OpenFOAM和离散元软件LIGGGHTS建立的水流-泥沙运动耦合模型对后台阶下游三维水流流动及泥沙的起动和输运进行了数值模拟。结果表明,动态一方程紊流模型能较好模拟台阶下游时均流场、紊动强度以及雷诺应力的分布,通过耦合模型计算得到的台阶下游泥沙起动概率以及床面输沙率分布与实验结果符合较好。计算结果揭示在台阶下游复杂水流条件下,紊流结构及涡旋运动对泥沙起动有重要作用,而时均流动对床面输沙起关键作用。

Using computational fluid dynamics software OpenFOAM and particle motion simulation software LIGGGHTS, a coupled fluid-particle model was presented and applied in the investigation of three-dimensional turbulence, sediment incipience and sediment transport at the downstream of the backward-facing step flow. The simulation results show that the dynOneEqEddy LES model can describe the mean velocity profile, the turbulence intensity and the distribution of Reynold stress well. The probability of sediment incipience and the sediment flux obtained by the coupled model at the downstream of the backward-facing step agree well with the experiment. The results indicate that the turbulence and large-scale vortices induce the sediment incipience and the mean flow contributes to its transport in the case of complex flows at the downstream of the backward-facing step.