Research On Numerical Simulation Of Flow In Flood Detention Area

The system of flood control projects consist of flood detention areas, dikes, reservoirs, etc. The flood detention areas play an important role in flood control in china. With the development of computer technology, it is an effective method to simulate the process of flood propagation in food detention areas by the numerical simulation. The horizontal 2-D flow mathematic model has been used to simulate the process of flood propagation in food detention areas by many scholars around the world. Based on the previous achievements, this paper studies method of numerical simulation in the flood detention areas, and some improvements was obtained: (1) The 2-D flow mathematic model in the flood detention area has been introduced and applied to practical projects. (2) Considering the existing of rivers in flood detention areas, the paper has improved the former 2-D flow mathematic model. (3) Aiming at the dentate boundary problem which is brought by the traditional Cartesian method, the paper employs the diagonal Cartesian method to improve the former 2-D flow mathematic model. (4) The paper discusses the numerical simulation of opening in the flood detention area, and builds a mathematic model to simulate the widening and scouring process of opening.There are 6 parts in this paper, they are arranged as follows:Part 1 is the introduction, it gives the object and the aim of study in the paper. The present situation, the main problems and numerical methods of the horizontal 2-D flow and sediment mathematic model are formulated systematically. Based on these, the main work of the paper is put forward.The 2-D flow mathematic model in the flood detention area is applied to the flood detention area of the DongXi Lake in Part 2. Considering the two situations of the freeway project and the high-tension transmission line project running through the flood detention area, the paper appraises the effects of the two projects in the flood detention area.Part 3 improves the former 2-D flow mathematic model and sets up a new one, which considers the situation of the barrel-drain existing in flood detention areas and the different hydraulic characteristics of flood between the barrel-drain field and out of the barrel-drain. The new mathematic model can be used for the barrel-drain with embankment or not. It agrees with the fact better.Aiming at the dentate boundary problem which is brought by the traditional Cartesian method, Part 4 introduces the diagonal Cartesian method to improve the former 2-D flow mathematic model. Comparison of simulated results shows that the improved model can give more reasonable flow characteristic. Finally, it is applied to the flood detention area of the Longgu Lake and Chendi Lake, and obtains satisfactory results.Part 5 studies the simulating method of the opening in the flood detention area. It divides the opening's widening and scouring process into four continuous parts: bed scouring, lateral erosion, dike failure and amending the bed configuration. Applied to general model, the new mathematic model is reasonable to simulate the opening's widening and scouring process.Part 6 sums up the whole paper and prospects further research work in the future.