【作者】 解刚；

【导师】 刘兴年；

【作者基本信息】 四川大学 ， 水力学及河流动力学， 2004， 硕士

【摘要】 数值模拟作为河流模拟领域的一个重要手段,已经在实际应用中发挥了越来越大的作用。传统的一维模型可以给出长河段的长期变形,并已经成功用于水库长期淤积计算、河道长期变形计算等。但对于复杂河道、弯道冲淤变化,深潭和浅滩的演变、水工建筑物附近的局部冲淤等问题,一维模型显得束手无策,这些问题的解决在数值模拟上有赖于平面二维或三维泥沙数学模型。三维模型计算复杂,速度较慢,二维模型的优点就凸显出来。传统的平面二维模型主要应用于河口、海湾、湖泊以及下游河段等宽浅水域,而能够用于山区河流计算的模型并不多。本文根据山区河流的特点,对传统的二维模型进行改进,建立了山区河流平面二维推移质数学模型。由于山区河流边界复杂极为不规则,本文采用了贴体坐标网格剖分求解域,在边界附近保持网格的正交性,又可以控制网格的疏密,保持网格的平滑。对贴体坐标系下的水流控制方程采用有限差分 ADI 法离散,对离散化后的方程组用追赶法求解。该方法稳定性好,运算速度快,同时占用内存少。在边界处理上采用“冻结”法,该方法可以方便的处理水边线问题,同时又可以使计算连续,不会带来流量的损失。模型中还对地形、水深等进行了平滑、概化,可以避免深潭、浅滩等急变形给模拟带来较大的误差。泥沙模型中,将床面按可动层分层来计算,可以方便地计算各层泥沙级配。根据非均匀沙的特点建立非均匀沙起动切应力公式,将其引入二维模型计算,使模型能够用于非均匀沙的计算。对岷江都江堰外江河段进行了流场和推移质冲刷模拟计算。并与实验资料<WP=4>四川大学硕士学位论文 山区河流平面二维泥沙数学模型进行了对比,结果表明该模型能够用于山区河流的计算。此外还尝试性的采用CFD 商业软件 Fluent 的欧拉固液两相流模型对万源州河、沱江金堂河段进行了推移质模拟研究。与实验结果对比分析表明两相流模型能够用于推移质计算,但在建体、边界处理等问题上还需要进一步研究。更多还原

【Abstract】 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 and<WP=6>Two-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.更多还原