Two-Dimensional Flow And Sediment Numerical Model For River Of Mountain Area

Numerical simulation has played more and more important roles in practice as asignificant means in the field of river simulation. Traditional one-dimensionalnumerical model can be used for simulating the long-term fluvial process of longreach, and has been applied triumphantly in the simulation of long-termsedimentation in reservoir and long-term evolution of long reach, etc. But for thecomplex channels, evolution of curved channels, evolution of deep pools and shoals,localized erosion and deposition occurred near hydraulic engineering constructions,one-dimensional model can't be used, and these problems can be solved by the useof two-dimensional or three-dimensional models. For Three-dimensional model, thecalculating is very complex and time-consuming, so two-dimensional model'sadvantages display outstandingly. Traditional horizontal 2-D models are mostly usedin the wide and shallow water area, such as embouchure, bay, lake, low reaches of ariver, etc, but those that can be used for modeling rivers of mountain area are few. Inthis paper, based on the characteristic of rivers of mountain area, two-dimensionalflow and sediment numerical model for river of mountain area is established. For theboundaries of river are not inerratic very much, the body-fitted coordinates grid isused. This grid can maintain uprightness near the boundaries, and can controlspacing and maintain smoothness. The finite difference scheme for governingequations of flow in body-fitted coordinates is ADI method, and the solution ofmatrix is evaluated with pursuit method. This method has better stability andTwo-Dimensional Flow and Sediment Numerical Model for River of Mountain Areaefficiency. With the unstable boundary problem, the freezing process is introduced,therefore the waterside curve problem is solved easily, and the calculating isconsecutive and the drainage is not reduced also. In addition in the model bedlandform and depth of water are smoothed, so the bad error arising from deep poolor shoal can be avoided well. For the calculating of sediment, the bed load in bedsurface is divided into several movable layers, so the sediment gradation in bed canbe calculated easily. According to the characteristic of non-uniform sediment, theformula of incipient shear stress of non-uniform sediment is presented and isintroduced in the model. So this model is fit for the calculating of non-uniformsediment. This model is employed in numerical modeling of flow and sediment ofWaijiang reach of Minjiang River in Dujiangyan, and compared the numericalresults with experimental data, the results indicate that this model can be applied inthe modeling of rivers of mountain area. In addition, the channels of WanyuanZhouhe River and Jingtang reach of Tuojiang River are modeled with eulerianmultiphase model in commercial software Fluent, and the comparison between thistry's results with experimental results indicates that this model can be applied in thecalculating of bed load, but there are many problems to be studied.