Numerical Simulation Of Low--Sedimentconcentration Flow Using Mixtur Model Of Multiphase Flow

Sediment transport in river not only brings trouble with production, but also with environment. Studying movement and distribution of sediment in the flow is precondition to solve the problem. Sediment transport has been studied by a lot of researchers, and a great deal of research results have been obtained, but it is not perfect. So, it is necessary to further study movement and distribution of sediments in the flow. In last years, the theory for multiphase flow, which combines turbulence model, was applied to the sediment transport, but infrequent. From this aspect, the application of the mixture model for multiphase flow to the flow at low sediment concentration would be studied in this thesis.In the thesis, the model for one-phase flow and the mixture model for multiphase flow used were be introduced, and computational software was explained and numerical methods were chose.The model was validated by comparing with experiment's result of sediment-carried water at low sediment concentration in flume. The flow carried sediments with three different diameters respectively was simulated. After comparing computational dates and experimental results of velocity and turbulent intensity at cross section in the middle of flume, some results are concluded: the computational results of velocity of flow coincide well with the measured data; the variational trend of turbulent intensity computational andexperimental results is same along with sediments whose diameters are smaller and bigger increased in the flow , but is different along with sediment increased whose diameters are between both kinds above. Then, two kinds of flow whose concentration was same carried sediments with different diameters were simulated, the qualitative analysis of distributing of sediments was done and considered reasonable. So, the mixture model for multiphase flow was considered that it can simulate characters of the flow carried sediments to some extend.The flow and movement of sediments of Yazidang Reservoir were simulated with the model for one phase flow and the mixture model for multiphase flow. And distribution in the reservoir and volume fraction at the outlet of sediments with different diameters were displayed. From the computational result, it was the conclusions that sedimentation is more obvious, the capability of the flow carrying sediments becomes weaker, and sediments filled up easier when the diameter of sediments becomes bigger.