局部断面收缩的溃坝水流三维数值模拟

Three-dimensional numerical simulation of dam-break water flow with local cross-section reduction

为研究局部断面收缩对溃坝水流传播的影响,采用压力隐式算子分割法求解雷诺时均方程和RNG k-ε紊流模型,建立了模拟三维局部断面收缩情况下溃坝洪水演进过程的数学模型。采用有限体积法对溃坝水流的控制方程进行离散,利用流体体积函数法处理自由水面,物理变量采用交错网格布置,对局部断面收缩溃坝水流进行数值模拟计算,模拟结果与实体模型试验结果吻合较好。利用该模型研究了溃坝洪水负波的形成和传播过程,得到了负波形成和传播的规律以及溃坝水流的水位变化特征。

A three-dimensional mathematical model that simulates the dam-break flood routing process that occurs during local cross-section reduction has been built to investigate the effects of local cross-section reduction on dam-break flow propagation. By calculating Reynolds-averaged Navier-Stokes equations basing on pressure implicit with splitting of operators( PISO) , the model is built on the basis of the RNG turbulence model. The governing equations of dam-break flow are discretized with the finite volume method, the free surface flow is dealt with using the fluid volumetric function approach. The physical variables are arranged on a staggered grid, and then the values of dam-break flow with local cross-section reduction are simulatively calculated. The simulation results are in agreement with physical model test results. The formation and propagation process of negative waves in a dam-break flood were examined with the model. The formation and propagation laws of negative waves as well as the variation characteristics of the water level were obtained.