Research Of Depth-Averaged Two-Dimensional Hydrodynamic And Sediment Transport Numerical Model In The General Curvilinear Coordinates

With the vigorous development of hydroelectric construction in our country, the hydrodynamic and sediment transport numerical model has made great progress, which is due to the advantage of low cost, quick speed and the flexible way. It has become an important means that studies the hydrodynamic and sediment transport laws and the evolution process of river bed. It is playing the more and more vital role in the production practice. On the basis of the wide research to the existing hydrodynamic and sediment transport numerical model, the transformation of the general curvilinear coordinates and the collocated grid system are brought into the depth-averaged two-dimensional hydrodynamic and sediment transport numerical model. Based on the collocated grid system, the depth-averaged two-dimensional hydrodynamic and sediment transport numerical model in the general curvilinear coordinates is built in this thesis.Comparison with the depth-averaged 2D hydrodynamic and sediment transport numerical model that is built in the orthogonal curvilinear grid and the staggered grid system, the model which is based on the general curvilinear coordinates and the collocated grid system isn't limited by the effect of orthogonality. And the grid generation is easy and flexible in the kinds of model. It can simulate the irregular boundary of the nature river better than the model else, and it has the even more strong adaptability. Furthermore, the using of the collocated grid system can reduce the amount of work in writing the program and calculation. As a result, the calculation efficiency is raised.In view of above-mentioned viewpoint, the generation method of the general curvilinear grid is studied in the thesis. Moreover, the governing equations of the model are transformed from the forms in the rectangular coordinate to the forms in the general curvilinear coordinate. Then the finite volume method and SIMPLE algorithm are used to settle the problem of the governing equations'discretization and solution. During the governing equations'discretization, the physical variables are located in the collocated grid system.Because the model in the thesis is aimed at the northern alluvial river, only the suspended load is considered in the model. Since the sediment is non-uniform in the nature river, the suspended load is grouped according to the grain diameter. In every group, the mean grain diameter is regarded as the representative grain diameter. And then the non-uniform suspended load in every group can be treated as the uniform suspended load. In terms of the point, the suspended sediment concentration and channel changes of every group can be calculated. Through accumulating the values of every group, the total value will be gained.The depth-averaged two-dimensional hydrodynamic and sediment transport numerical model in the general curvilinear coordinate, which is built in the thesis, is proved and tested through the simulation calculation that is carried out on the rectangular continuous curve and single-sudden-expansion channel. The results show that the flow field and the evolution of river bed are simulated successfully in the model. And the model is feasible in theory.