宽浅型明渠非定常流的数值模拟

本文根据不可压缩三维非定常流的动量方程和连续方程,求解了宽浅型明渠中三维流速分布和水位随时间的变化规律.采用单方程湍流模式确定涡粘性系数,沿垂向引入无尺度坐标,使计算网格能拟合自由面及床面.对控制方程采用有限差分离散、剖开算子法求解.通过引用欠松驰技术,提高了计算稳定性.计算表明,本文中提出的计算方法具有时间步长大、存储量小和机时省的优点.最后,用其求解长江口南港河段的潮流运动,计算结果与现场实测结果十分一致.

Numerical Simulation of Unsteady Flows in Open Channels with Large Aspect Ratios

On the basis of three-dimensional equations of motion and the equation of continuity of the incompressible unsteady flow , the three dimensional velocity distribution and variation of tidal levels with.time in well-mixed tidal estuaries have been solved . The energy-equation turbelence model is used to compute the eddy viscosity coefficient . A dimensionless vertical coordinate is introduced so that the computational meshs can conform the free water surface and the bed of the waters, The finite difference method is used to discretize all the governing equations. The operator splitting technique is used to solve them . The under-relaxation technique is employed so that the stability in computations could be increased . Computations show that the present method makes it possible take large time stepand save computer storage required and cut the run period of the computer. The method has been used to solve tidal flows in the South Passage of the Yangtze Estuary. It can be seen that the calculated results are in good agreement with the field data.