基于MP-PIC方法的泥沙静水沉降三维数值模拟研究

Three-dimensional numerical simulation of particle settling in still water based on MP-PIC method

以MP-PIC模型为基础,采用Eulerian-Lagrangian方法,建立了描述泥沙静水沉降的三维数值模型,研究了网格敏感性、单颗粒沉速和群体颗粒制约沉降等问题。结果表明,当采用2~5倍泥沙粒径的网格尺度时,颗粒沉速模拟结果与已有经验公式相差较小,推荐使用该尺度网格模拟泥沙颗粒运动。不同粒径单颗粒泥沙沉速模拟结果与已有实验结果及经验公式吻合较好,模型可以描述不同大小泥沙颗粒运动。不同体积浓度的群体颗粒沉降特征具有中间区域颗粒沉速较大,靠近边壁处沉速较小的趋势,与Peysson等人的实验结果一致,同时群体颗粒制约沉速与理论公式也较为接近,采用MP-PIC方法能够很好地对泥沙颗粒静水沉降进行三维数值模拟研究。

A three-dimensional numerical model was applied to describe particle settling in still water based on the multiphase particle-in-cell(MP-PIC)method,which is a form of Eulerian-Lagrangian approach.The sensitivity of grids,the settling velocity of single particle and the hindered settling of group particles were studied.The results show that when the ratio of mesh size to particle diameter is equal to 2-5,the simulation results of particle settling velocity have little difference with the empirical formulas.It is recommended to simulate the sediment motion on this grid scale.The simulation results of single particle settling velocity with different particle sizes are in good agreement with the experimental results and empirical formula.Therefore,it can be indicated that the model can describe the sediment settling with different particle sizes.As shown by experiments of Peysson et al.,the simulated group particles settling velocity in the middle region is also larger than that near the wall boundary for different volume concentrations.At the same time,the hindererd settling velocity of group particles is close to the theoretical formula.Three-dimensional numerical simulation of particle settling in still water can be carried out based on MP-PIC method.