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A depth-averaged numerical model for simulating heat and fluid flows in vegetated channels.

机译：一个深度平均数值模型，用于模拟植被通道中的热量和流体流动。

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摘要

In this thesis, a complex depth-averaged model is developed for simulating heat and fluid flows in vegetated channels, with a capability to simulate dam-break and flooding phenomena. The model is able to simulate both laminar and turbulent flows, it can take the secondary flow effects of any kind into account, it uses the latest developments in porous media science in order to simulate the flow in vegetated zones, and it is able to perform either a dimensional or a dimensionless solution. This depth-averaged model is able to start a solution from scratch or perform a hot start, it uses many innovative techniques to automatically minimize the computational cost for problems which include huge number of computational cells, it uses many innovative techniques for increasing the accuracy of solutions, it supports variety of boundary conditions, it can perform a high-order solution, and it supports several techniques for controlling the residual errors.;As the first step, a two-dimensional numerical code is developed for simulating heat and fluid flows. The transport equations are solved using a collocated unstructured finite-volume scheme. Both numerical and experimental data are extensively used in order to validate the code for various flow conditions. A Multi-Block Local Triangulation (MBLT) technique is developed and successfully applied to several simulations for reducing the absolute magnitude of the oscillations in pressure field. In this technique, a solution for reducing the absolute magnitude of pressure oscillation is innovatively looked for through grid rather than the transport equations for mass and momentum. The MBLT technique can be simply applied to complicated geometries. This property makes the MBLT technique desirable to be used in engineering software.;The validated two-dimensional code is then extended to a depth-averaged code where, the depth-averaged code itself is validated against additional experimental and numerical data. A vorticity equation is also added to the depth-averaged code in order to take the secondary flow effect into account. The depth-averaged transport equations are written in an innovative way, and the source terms due to the channel bed are also discretized with an innovative method. When the water depth is very small, application of these techniques eliminates the oscillations from the profile of water surface. An appropriate choice of grid for the depth-averaged simulations is then suggested through investigating the solution of depth-averaged transport equations on various grids and flow conditions. An innovative method, Total Value – Linearly Interpolated (TV-LI), is also developed for interpolating variables from cells center into the cells faces. This technique reduces the computational cost and, the amount of reduction in computational cost increases when the number of cells increases.;The depth-averaged code is further extended to include the capability to simulate streams with moving boundaries where the position of water edge is a function of time and space. An innovative method is suggested for controlling the water depth in shallow regions in order to prevent formation of zones with spurious negative water depth. An innovative high-order technique is developed for treating the wetting-drying fronts, and is added to the depth-averaged code. This high-order technique eliminates formation of spurious thin layers of water which normally form and extend downstream when a low-order wetting-drying technique is used. As an important advantage of this feature, the solver will solve the transport equations only in actual wet regions. This will keep the computational cost minimized.;The models which are developed in this thesis are aimed to be used for engineering applications such as dam-break and flooding, channel flow, vegetation, and thermal pollution. All models are developed based on sub-program, module, subroutine, and function concepts and, in turn, it is easily possible to extend them to new applications. The two-dimensional model is also extendable to a three-dimensional model. (Abstract shortened by UMI.).
机译：本文建立了一个复杂的深度平均模型，用于模拟植被通道中的热和流体流动，并具有模拟溃坝和洪水现象的能力。该模型能够模拟层流和湍流，它可以考虑任何形式的二次流影响，它利用多孔介质科学的最新发展来模拟植被带中的流动，并且能够执行维或无量纲的解决方案。这种深度平均模型能够从头开始解决方案或执行热启动，它使用许多创新技术来自动最小化包括大量计算单元在内的问题的计算成本，它使用许多创新技术来提高精度。解，它支持各种边界条件，可以执行高阶解，并支持多种控制残差的技术。作为第一步，开发了二维数值代码来模拟热量和流体流动。使用并置的非结构化有限体积方案来求解运输方程。数值和实验数据均被广泛使用，以验证各种流量条件下的代码。开发了多块局部三角剖分（MBLT）技术，并将其成功应用于减少压力场中振荡绝对幅度的几种模拟中。在这项技术中，通过网格而不是质量和动量的输运方程式，寻求了一种降低压力波动绝对幅度的解决方案。 MBLT技术可以简单地应用于复杂的几何形状。此属性使MBLT技术可理想地用于工程软件中。经过验证的二维代码随后扩展为深度平均代码，其中，针对其他实验和数值数据对深度平均代码本身进行了验证。涡度方程也被添加到深度平均码中，以考虑二次流效应。深度平均输运方程式以创新的方式编写，并且由于创新的方法也离散了由于河床引起的源项。当水深很小时，这些技术的应用消除了水面轮廓的振荡。然后，通过研究在各种网格和流动条件下的平均深度运输方程的解，建议为深度平均模拟选择合适的网格。还开发了一种创新的方法，即“总值-线性插值（TV-LI）”，用于将变量从单元格中心插值到单元格面。该技术降低了计算成本，并且随着单元数量的增加，计算成本的减少量也随之增加。深度平均代码进一步扩展，包括了模拟具有移动边界的流的能力，其中水边缘的位置是时空的功能。提出了一种创新的方法来控制浅水区的水深，以防止形成具有伪负水深的区域。开发了一种创新的高阶技术来处理润湿干燥前沿，并将其添加到深度平均代码中。这种高阶技术消除了水的杂散薄层的形成，当使用低阶湿法干燥技术时，这些杂散薄层通常形成并向下游延伸。作为此功能的重要优点，求解器将仅在实际潮湿区域中求解运输方程。这将使计算成本降到最低。;本文开发的模型旨在用于诸如水坝溃坝和洪水，河道流量，植被和热污染的工程应用。所有模型都是基于子程序，模块，子例程和功能概念开发的，因此很容易将它们扩展到新的应用程序。二维模型也可以扩展到三维模型。 （摘要由UMI缩短。）。

著录项

  • 作者

    Moradi Larmaei, Mohammad.;

  • 作者单位

    Ecole Polytechnique, Montreal (Canada).;

  • 授予单位 Ecole Polytechnique, Montreal (Canada).;
  • 学科 Engineering Civil.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 274 p.
  • 总页数 274
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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