高含沙水流的紊动粘性系数研究及其应用

基于张红武的“紊流涡团模式”和采用高精度的流速垂向分布表达式,建立起高含沙水流的紊动粘性系数计算公式。应用此公式计算泥沙连续性方程中的泥沙扩散系数,得到了与测试资料相符合的含沙量垂线分布规律;进一步,将建立起的紊动粘性系数计算公式应用于黄河下游平面二维泥沙数学模型中,以封闭水沙控制方程,并选择1982年洪水和花园口至夹河滩河段开展数值仿真,计算出的洪水流量过程、水位过程及主流线等与实测资料基本一致。应用结果表明本研究中所建立的紊动粘性系数计算公式可用于高含沙水流的理论分析和模拟计算中。

STUDY ON TURBULENT VISCOSITY OF HYPER-CONCENTRATED WATER FLOWS

Based on the vortex blob theory suggested by ZHANG Hong-Wu, a formula of turbulent viscosity for hyper-concentrated flows is derived by using an high accuracy expression for vertical distribution of velocity. This formula is used to calculate the sediment diffusion coefficient in sediment continuity equation, and an expression is obtained for the vertical distribution of suspended sediment concentration, which is validated by the measured data from both laboratories and fields. A two-dimensional mathematical model for unsteady sediment transport in the Lower Yellow River is developed by employing this formula of turbulent viscosity to close the governing equations for sediment and water and the 1982 flood in the Lower Yellow River from Huayankou to Jiahetan with a length of 100 km is numerically simulated with the model. The computed results, such as the discharge, water stage, velocity field and main current agree well with the measured data. The application results indicate that the formula of turbulent viscosity derived in this work is applicable to hyper-concentrated flows.