Three-dimensional Mathematical Model Of Turbulent Flow And Sediment Transport And Its Applications

Turbulence models have been used extensively in flow calculation. The K-z model is the well known model for its efficiency and reasonable accuracy. However, the standard K-z model, because of the assumption of isotropic eddy viscosity, appears to be deficient in predicting flows of complex turbulent flow. Dou Guoren presented a Reynolds stress model for the anisotropic turbulent flow, in his study on "Stochastic Theory of Turbulence". Also, he improved the expressions of the Law of the Wall. His theory has wide application potential in the calculation of 3-D turbulent flow.In this paper, based on the two-dimensional mathematical model of turbulent flow and sediment transport developed by author and Dou's stochastic theory of turbulent flow, a three-dimensional mathematical model of turbulent flow and sediment transport has been developed. The main contents of this work are as following:(1) A 3-D mathematical model of turbulent flow, based on the K-e model, is developed to simulate the flow around the spur-dike, and the result shows that the model can predict the 3-D characteristic of flow.(2) The 3-D turbulent flow model is further improved by using Dou's stochastic theory of turbulent flow and the 3-D flow fields in a navigation channel are calculated. The results is agreement with flume experiment data.(3) Based on the 3-D turbulent flow model, by introducing the three-dimensional suspended-load transport and the bed material sizedistribution equations, a 3-D turbulent flow and sediment transport mathematical model is developed. The water level is determined from a two-dimensional Poisson equation derived from two-dimensional depth-averaged momentum equations. The governing equations are solved numerically with a control method. The model was tested for channel flow situations with net entrainment from a loose bed and with net deposition, and the field data in the reach from Miaohe to Sandouping of the Yangtze river before and after the Gezhouba project was constructed. The calculated is agreement well with the measured data.The model is applied to predict the sediment deposition of the Three Gorges Project. The computed deposition process and its distribution, the bed material size distribution and the flow velocity, the suspended sediment concentration in different term and elevations are in good agreement with the results of physical model by Tsinghua University, Research Institute of Yangtze River and Nanjing Hydraulic Research Institute.