【作者】 赵东淼；

【导师】 唐军；

【作者基本信息】 大连理工大学 ， 水利工程， 2012， 硕士

【摘要】 对于泥沙的研究,由于三维数学模型的复杂性,通常根据问题的性质以及地形和水流特征进行简化。在研究水力特性沿侧向变化不大而垂向上有明显差异区域的泥沙运动时,垂向二维泥沙模型基本能够满足需求,且相较三维模型而言,输入数据少,计算效率高。基于Youngs-VOF法,由精度较高的ELVIRA法取代Youngs-VOF法中传统的自由面法向确立方法,耦合Reynolds时均方程、非线性k-ε紊流模型及泥沙输运模型,建立了垂向二维泥沙输运模型。紊流模型和悬沙输运模型采用水平显式,垂向隐式的power-law格式进行求解,而床沙输运模型则采用稳定性较好的欧拉加权基本无振荡迎风格式(Euler-WENO)求解。在底部边界处理上,采用了壁函数法则及网格封闭技术。利用所建立的垂向二维水流模型对带精确解的一维经典浅水问题、孤立波爬坡问题及带槽沟明渠水流运动问题进行了数值模拟,分析了模型的数值稳定性、和谐性、适应性、激波捕捉能力。在此基础之上,利用建立的泥沙输运模型进对净冲刷、净淤积和深槽回淤的水槽试验进行了数值模拟分析。由数值分析的结果可知,本文建立的垂向二维泥沙输运模型是有效的,且对自由面非线性有着将强的适应性,对涌潮这类强间断水流作用下的泥沙输运研究有着重要的借鉴意义。更多还原

【Abstract】 Because of the complexity of the three dimensional mathematical model, usually, the research of sediment is simplified according to the topography, the flow characteristics and the nature of the problem. And the2-D vertical sediment model can do quite well in researching the sediment transport where the hydraulic characteristics change little along the lateral while obviously in the vertical direction. Compared to the3-D model, the2-D model requires fewer dates, and is more efficient.In this paper, a2-D vertical model of sediment transport was established by coupling with the time-average Reynolds equations, the k-ε nonlinear turbulence model and the sediment transport model based on the Youngs-VOF method that free surface normal was obtained by ELVIRA method. The turbulent model and suspended sediment transport model were discretized with implicit in the vertical coordinate and explicit in the horizontal coordinate based on the power-law scheme, and bed sand transport model was solved by Euler-WENO scheme. The wall function law and the technique of grid-closing were introduced in dealing with the bottom boundary.Using the established flow model, the1-D shallow water problems having exact solutions, the experiment of solitary wave runup and rundown, and the experiment of steady flow crossing the trench were simulated to analyse the numerical stability, adaptability, shock-capturing property, and the accuracy of the numerical results of the model. On this basis, the experiment of net entrainment from a loose bed, net deposition and evolution of the trench were simulated and analysed by the sediment transport model.The results indicated that the2-D vertical sediment transport model established was effective, and had strong adaptability for nonlinear free surface, could have a good reference for the research of sediment transport driven by the flow with strong discontinuity.更多还原