【作者】 李勇；

【导师】 余锡平；

【作者基本信息】 清华大学 ， 水利工程， 2007， 博士

【摘要】 建立在高水平数值模型基础上的悬移质泥沙运动研究不仅具有重要的理论意义,也具有重要的应用背景。随着近十几年随着两相流理论与数值方法的发展,加上计算机硬件能力的大幅度提升,应用两相流模型研究低浓度含沙水流问题已逐渐成为可能。本论文从稀疏两相流的双流体模型基本方程出发,借鉴气固两相紊流理论,建立了低含沙量问题的通用数学模型,同时构建了有效的数值计算方法,编写了相应的计算机程序。并在多种条件下对数值模型进行了验证。论文应用建立的数学模型对单向流条件下的悬移质泥沙运动进行数值计算,并用已知的实验成果对数值模型进行了验证。研究了恒定流中泥沙浓度及扩散系数沿垂向的分布规律,并就泥沙沉降规律以及含沙水流紊动结构等问题进行了讨论,还探讨了两种常用的颗粒相紊流模型的优缺点及其适用范围。论文应用建立的数学模型也对边界层往复流条件下的悬移质泥沙运动进行数值计算。通过与实验结果的对比,分析了边界层水流运动结构的特征以及泥沙浓度分布的规律,探讨了往复流作用下各类相间作用力的时空变化规律及其对悬移质泥沙运动的影响。论文还应用建立的数学模型对波浪作用下的悬移质泥沙运动进行了数值计算。研究了波浪作用下悬移质泥沙浓度的垂线分布规律,探讨了波浪作用下各类相间作用力的时空变化规律及其对悬移质泥沙运动的影响,采用基于颗粒轨道模型模拟了单颗粒泥沙对于紊动作用以外的相间作用力的反应。还就波浪作用下的输沙率进行了初步的探讨。更多还原

【Abstract】 Development of advanced numerical models for sediment-laden flows is of current significance because improvement of our understanding on sediment transport phenomena in coastal environment has been pushed for decades to meet the requirement from engineers who are in charge of planning, design, or construction of coastal and harbor facilities. With the enhancement of two-phase flow models and advances in numerical methods, it is now possible to apply numerical models to study sediment transport problems with low concentration. This thesis is based on newly derived governing equations of sediment-laden flows. Relevant numerical method is also proposed. The numerical model is extensively verified.Suspended sediment transport under unidirectional flow condition is investigated. Vertical distributions of the sediment concentration and the diffusion coefficient are carefully discussed. The effectiveness of two turbulence models, i.e., Ap model and k p model, is also studied. Suspended sediment motion in the boundary layer under oscillatory flow condition is also studied. The characteristics of the turbulent flow and its resulted sediment transport in the boundary layer are demonstrated. Variation of the various inter-phase forces in the time and space are examined.To consider sediment transport under wave motion, numerical methods are established so as to represent wave-making and wave absorbing, and to trace the free surface, under two-phase flow conditions. The numerical model is then used to compute the vertical distribution of the averaged sediment concentration within a wave period. Variation of the various inter-phase forces in the time and space are shown. Sediment transport rate under waves is also briefly discussed.更多还原