【作者】 梁书秀；

【导师】 孙昭晨； 沈永明；

【作者基本信息】 大连理工大学 ， 港口、海岸及近海工程， 2000， 博士

【摘要】 污水排入大水体后，在排放口附近污水与环境水体剧烈掺混，流速、污染物浓度、紊动特性变化都很大，称之为近区。而在近区之外的污水所能影响的水域称为远区。这两个区的水动力特性相差很大。在近区主要是射流运动性质，称为近场；在远区属随流扩散性质，称为远场。一般来说，应该用不同的数学模型来模拟。本文正是针对近场、远场的差异，发展和采用了不同的数学模型，对保守性物质的输移扩散进行了数值研究。研究工作分为两篇，共十二章。 第一篇：近场的数值模拟 采用深度平均的应力—通量代数全场模型，用来模拟热水或污染物侧向排入大水体的各向异性的输移扩散规律。模型中给出了应力分量新的表达方式，并采用了深度平均的连续、动量、标量方程。本文首次将深度平均的应力—通量代数模型应用到具有潮汐流性质的流动中。第一篇的主要工作包括五部分：1．概述。第一章简要介绍了紊流模型的发展、两方程紊流模型和应力—通量代 数模型的研究现状。在较全面地了解与本课题相关领域研究现状的基础上提 出本文的工作。2．模型的基本内容。包括文中的第二章和第三章。第二章中简述了深度平均的 应力—通量代数模型的推导过程和基本内容；第三章给出了模型的数值计算 方法。3．定常流下的数值模拟。文中的第四章用该模型模拟了定常流下明渠热水侧向 排放问题。计算所得的回流区形状及温度场分布与深度平均的k—ε模型及 实验结果对比表明，本文的计算结果与实测值符合得较好，验证了该模型模 拟此类问题的准确性。应力分量的模拟结果体现了模型的各向异性。4．非定常流下的数值模拟。流动的性质为具有潮汐性质的非对称潮流。结果给 出了一个周期内流场、污染物浓度场随时间的变化规律，并同现有的其他模 型和实验相比较，进一步验证了本文模型在处理明渠排放问题方面的优越 性。此部分内容是本文的重要工作之一。5．讨论。针对数值模拟中遇到的问题，第六章给出了关于流场结构和计算区域 的讨论以供参考。 大连理工大学博士论文一 第二篇：远场的数值模拟 采用一种半隐式的三维海洋紊流模型对杭州湾及长江口附近的潮流场、盐度场进行了数值模拟。该海洋紊流模型在垂向上采用。坐标，可以较好地处理表面和底层，提高浅水时的垂向分辨率。第二篇的主要工作包括四部分：1，概论。第七章综述了三维潮流模型的发展和研究现状，总结了模型之间的差 异，从而提出了远场数值模拟中模型选用的原因。2．模型的基本内容及特点。包括第八和第九两章。第八章简要介绍了该紊流模 型的发展、基本内容、模型的显著特点。第九章给出了数值计算方法。3．潮流场的数值模拟。用该模型对杭州湾及长江口附近的大、中、小潮的潮流 场进行了模拟，潮流的潮位和潮流流速的模拟结果与实测值符合良好。从而 验证了该海洋紊流模型可用于近海水域水动力特性的模拟，并且有较强的对 复杂地形的适应能力。4．浓度场的数值模拟。首先，通过对点源的二维、三维问题的模拟，验证了该 模型的数值格式可用于浓度场的模拟。其次，通过对杭州湾附近盐度场的模 拟，进一步说明了该模型可用于近海海域物质的输移扩散的研究。 本文在对近场的数值模拟中，采用的是深度平均的应力一通量代数模型。文中在验证了该模型预测紊流的准确性之后，成功地将该模型应用到潮汐流中物质输移扩散的模拟中，促进了该模型进一步向实用化方向发展。在远场的数值模拟中，首先，将三维海洋紊流模型应用到近海海域水动力特性的模拟中，验证了该模型的预测能力和对复杂地形的适应能力。其次，通过对点源对流一扩散问题的模拟，考察了该数值格式的精确度之后，成功地模拟了长江口和杭州湾附近的盐度场。更多还原

【Abstract】 Wastewater or heated water is frequently discharged instantaneously or intermittently into ambient flow. Near an ouffall, the discharged sewage mixes with the water of river or ocean. The velocity, pollutant concentration field and turbulent characteristics vary dramatically. This region is called the near-field. The water region beyond the near-field is called the far-field. The difference of hydrodynamic characteristics between the two regions is large. In the near- field, jet flow dominates while sewage is transported passively with ambient flow in the far-field. Usually, different mathematical models should be used. For this reason, different models are adopted and developed to simulate the transport and dispersion of conservative pollutants in this paper. There are two parts in the paper. Part 1: numerical simulation of the near-field. A depth-averaged mathematical model is developed to simulate anisotropic turbulent recirculating flows in an open channel, into which the heated-water is side-discharged. The model is an algebraic stress梖lux model (ASM) , which gives new expressions of stress components, and employs the depth-averaged continuity, momentum and temperature equations, which are solved by finite-volume procedure. This is the first time that depth-averaged ASM model is applied into the simulation of tidal flow. The work consists mainly of five aspects: 1. Introduction. Summarize the present research progress and application of two-equation turbulent flow model and ASM. The contents and numerical methods in the thesis are set forth. 2. Content of the model. It consists of two chapters. In the second chapter, the origin and content of depth-averaged ASM are introduced. Its numerical method is described in the third chapter. 3. Numerical simulation of steady flows. The flow and the concentration field are simulated when hot water is side-discharged into an open channel. Predicted size of the recirculation zone and isotherms are compared with those of experiment and the results of k ?e model. The results show good agreement with experiment data and logical trend of expansion of recirculation zone. The stress and flux components show the an isotropy of the model. 4. Numerical simulation of unsteady flow. The tide is asymmetric. The results show the changes of velocity field and pollutant concentration with time and space during one tidal period. The better agreement with experiment than depth-averaged k model verifies the superiority of the depth- averaged ASM. 5. Discussion on the model. Part 2: numerical simulation of the far-field. A semi-implicit three-dimensional ocean circulation model is employed to simulate the tidal flow of Hangzhou bay and Changjiang river estuary. a?coordinate is adopted in vertical direction, It permits the use of fine vertical resolution in the surface and bottom boundary layers. Both analytical solutions and real salinity field calibrate the numerical scheme. The work consists mainly of three aspects: 1. Introduction. In the seventh chapter, The development and present progress and application of three dimensional tidal model are summarized, the differences among these models are concluded. 2. Content and characteristics of the model. It is composed of two chapters. The development, content and the characteristics of the model are introduced in the eighth chapter while the numerical m更多还原