【作者】 董壮；

【导师】 王超； 陆永军；

【作者基本信息】 河海大学 ， 环境工程， 2003， 博士

【摘要】 在对近年来国内外三维紊流计算的有关文献进行了细致的分析研究基础上，本文将三维紊流计算中常用的σ坐标变换加以改进，引入垂向分层系数k₀，采用σ=k₀ （z-η）／D的变换方法，以期更好地与实际地形相匹配，改善常见σ坐标变换数学模型在地形复杂地区容易发散的问题，并给出了k₀的确定方法。根据上述思想，从雷诺方程出发，采用静压假定和包辛内斯克的紊动粘性系数假说，建立了新坐标系中的紊流控制方程组，同时给出了对物质输运过程具有代表性的盐度输运方程、相应的边界条件及完整的推导过程。分析了在新坐标系下应用k-ε模型可能存在的问题，并从模型的特点出发，以对数流速分布为基础，导出了垂向紊动粘性系数的分布公式。 采用有限差分法对新坐标系中的模型控制方程进行了数值离散，根据差分格式编制了相应的计算程序。分别对垂向二维恒定流的垂向流速分布，实验水槽三维恒定流的垂向流速分布与横向流速分布进行了计算，将计算结果与相应的实测资料以及理论结果对比分析，证明了模型的可靠性。在实验水槽恒定流的计算中，根据壁面函数法的基本原理，对槽底及壁面的边界条件做了相关的专门处理；并根据实验水槽恒定流的水力特性，导出了摩阻流速计算公式。 以地形复杂的瓯江河口局部海区为例，分别采用给定恒定流以及实际潮流过程作为边界条件，对水流盐度过程采用不同的k₀形式进行了计算，给出了潮位过程、平均盐度过程以及流场的逐时计算结果，将计算结果与相应的理论结果、实测资料以及大范围二维数学模型的计算结果进行了验证及细致分析，得到了较为满意的结果。 深入系统的总结了论文工作中有待进一步深入研究的问题，提出可能的解决方案，并探讨了后续的研究发展方向。 本文的主要创新之处在于： 1．引入垂向分层系数k₀，σ坐标变换加以改进，建立了新的完整的水流盐度数学模型，并给出了完整的推导过程； 2．在对新坐标系中k-ε模型进行细致分析的前提下，以对数流速分布为基础，采用新的方法导出了垂向紊动粘性系数的分布公式，并与传统的公式相比较，证明了其正确性； 3．采用有限差分方法对新建的数学模型进行了数值离散，通过稳定性对比分析证明了其可靠性，编制了完整的计算程序； 4．作为对新建数学模型、差分格式以及计算程序的检验，结合理论分析及实测资料，对实验水槽中的三维流动，以及殴江河口局部复杂海区的潮流盐度过程等多种工况进行了验证计算，取得了较为满意的成果。更多还原

【Abstract】 Based on the detailed and abroad investigation of the inland and overseas literatures three dimensional turbulence computation in recent 10 years, the vertical delaminating coefficient kowas introduced in normal σ - coordinate transform in this paper. This means σ = wasused to displace the normal σ, which has been regularly used in the computation of 3D flow in recent years. The use of new σ coordinate is aimed to match the landform better and improve the instance that the normal σ coordinate mathematic models are emanative with complicated landform sometimes. The way to get ko was given in this paper. By this way, the turbulence control equations were constructed from Reynold equations with static pressure supposition and Boussinesq’s turbulence viscidity coefficient supposition and the salinity transportation equations, which are representative of the matter transportation equations, are given. The integrated deduction and corresponding boundary conditions are also given. The potential problems related to the applications of k- model under the new coordinates are analyzed and the distribution formula of vertical turbulence viscidity coefficients is deduced on the base of logarithmic velocity of flow according to the characteristics of the model.The FDM is applied to the numeric discreteness of control equations under the new coordinates and the corresponding programs are developed. The reliability of the model is proved by the comparison between computation and observation in the following three cases, the distribution of vertical velocity of flow on two dimensional invariant flow, the distribution of vertical velocity of flow and transverse velocity of flow on three dimensional invariant flow in the flume. In the case of computation of invariant flow in the flume, the boundary conditions on bottom and wall of the flumes are managed specially according to the view of wall function method, and the formula about u* is deduced according to the hydraulic characteristic of invariant flow in the flume.In the part sea area of the Oujiang estuary which has complicated landform, the different ko are adopted in the control equations of flow and salinity process to work out the process of tide level, averaged salinity and the flow field using the invariant flow and the real process of tide level as the boundary conditions. The comparison and analysis among the computed results, the theoretic results and the computed results of two dimensional numeric model in a large area indicate that the model is applicable.The results are summed up deeply and systemically and the problems required further investigation are pointed out. Also, the promising approach is set forth and discussed initially.更多还原