泵站前池水沙流的数值模拟

Numerical simulation of slit-laden flows in pumping station forebay

针对泵站前池内的水沙流动,基于格子Boltzmann方法和大涡模拟思想,建立了二维浅水LBM-BGK模型和泥沙数学模型的联合计算模式,进行了水沙流的数值模拟研究.介观LBM-BGK模型采用了LES的亚格子尺度应力SGS模式模拟二维浅水方程,宏观二维平面泥沙数学模型包括悬沙输运方程、河床变形方程、水流的挟沙力公式等.水流与悬沙之间的求解方法采用非耦合解模式,即先求解出水流运动控制方程,再求解泥沙输运方程,推求前池底部的冲淤变化.最后,成功地模拟了泵站前池水沙流的流速分布、水深变化和旋涡的位置和尺寸,以及泥沙的冲淤变化,流速计算结果与试验结果比较吻合.计算结果表明:此联合计算模式在一定程度上客观地、较好地重演了前池内水流的基本流态以及泥沙的冲淤变化.

Based on a two-dimensional lattice Boltzmann method coupled with large eddy simulation（LES）,a LBM-LES model combined with sediment mathematic model is proposed for 2D silt-laden flows in a pumping-station forebay.Shallow water equations is numerically simulated by the mesoscopic LBM-BGK（Bhatnagar Gross Krook） model and the turbulence can be taken into account and modeled efficiently by a Sub-Grid-Scale stress（SGS） model.A macroscopic 2D horizontal sediment mathematic model consists of suspension transport equations,riverbed deformation equations,formula of sediment-carrying capacity,and so on.The segregating scheme is adopted to solve the governing equations for turbulent flows and sediment governing equations,i.e.,the solutions to the turbulence governing equations,suspension transport equations,and sediment erosion deposition along the forebay-bed are solved sequentially.Finally,the simulated velocity distribution is in agreement with the experimental data,and the depth distributions,the vortex position and size as well as the sediment erosion-deposition are successfully predicted in the forebay.All the calculation results agree well the hydrodynamic rules in nature.The numerical results show that this model can well reproduce the sediment-laden flow patterns,sediment erosion and deposition in the forebay,and the mathematical model and numerical algorithms are accurate,reliable and feasible to predict the sediment-laden flows in forebays.