Turbulence Closure for Energetic, low-Ri Stratified Shear Flows

高能、低 Ri 分层剪切流的湍流闭合

• 批准号: 0352047
• 负责人: Hartmut Peters
• 金额: --
• 依托单位: University of Miami
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-05-01 至 2008-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0352047&HistoricalAwards=false
• 关键词: Turbulence; Closure; Energetic; low; Ri

ABSTRACTOCE-0352047Stratified, low-Richardson number shear flows, which are of crucial importance in scientific and practical contexts, place high demands on turbulence closures. A turbulence closure model that can realistically simulate such flows will be developed by taking, and if necessary modifying, existing closures and to subjecting them to a three-step screening process. Step 0 is a demand that the closures have a realistic steady state for homogeneous, stratified shear flows such as in the laboratory experiments of Van Atta's group. In Step 1 the closures are tested in isolation in a strict quantitative comparison of simulated and observed turbulent dissipation rates and length scales. The observational basis of Step 1 are extensive microstructure measurements from the tidally driven Hudson River estuary. The demand on the closures in Step 1 is that, given the observed shear and buoyancy frequency, the closures produce a close match of the levels and tidal depth-time structure of the observed turbulent mixing. In Step 2 the closures are embedded in 2D and 3D numerical models of the outflow of saline water from the Red Sea. The demand on the closure here is that it allow the numerical models to reproduce the peculiar structure of the outflow which combines a core layer at the bottom that undergoes little entrainment and dilution over a distance of over 100 km while a thick shear zone above the core layer undergoes highly energetic turbulent mixing. The difference in performance of the closures in a non-hydrostatic 2D model and a coarser-resolution, hydrostatic 3D model will be explored. The 3D model allows investigating possible effects of rotation and of the outflow channel topography. The closure schemes which will be considered include the new closure by Baumert and Peters, the Canuto et al. closure which passes Step 0 after modification, another closure previously employed by Peters et al. and Mellor/Yamada which is being used ubiquitously.The broader impacts of the proposed research will be through improved management of coastal and estuarine waters as well as research into climate and climate change as a result of improvement of turbulence closures embedded in most widely used models. An educational component is given through the proposed participation of a graduate student.

Abstractoce-0352047 stratififed，低富丽堂子数字剪切流，在科学和实践环境中至关重要，对湍流关闭提出了很高的需求。可以实际模拟此类流的湍流封闭模型将通过采取和必要的修改来开发现有的封闭，并使它们进行三步筛选过程。步骤0要求封闭具有近似，分层的剪切流的现实稳态，例如在Van Atta组的实验室实验中。在步骤1中，在严格的定量比较中对模拟和观察到的湍流耗散率和长度尺度进行严格的定量比较，对封闭进行了分离。步骤1的观察基础是来自潮汐驱动的哈德逊河河口的广泛微观结构​​测量。步骤1中对关闭的需求是，鉴于观察到的剪切频率和浮力频率，闭合产生了观察到的湍流混合的水平和潮汐深度结构的紧密匹配。在步骤2中，封闭式嵌入了盐水从红海流出的2D和3D数值模型中。此处关闭的需求是，它允许数值模型重现流出的特殊结构，该结构结合了底部的核心层，在100 km以上的距离内很少受到夹带和稀释，而核心层上方的厚剪切区则经历了高能的湍流混合。将探索非静态2D模型中闭合性能的性能差异和更粗的分辨率，静水3D模型。 3D模型允许研究旋转和流出通道地形的可能影响。封闭方案将被视为包括Baumert和Peters的新封闭，Canuto等人。修改后通过步骤0的闭合，彼得斯等人先前使用的另一个闭合。正常使用的Mellor/Yamada。拟议研究的更广泛影响将通过改善沿海和河口水的管理以及对大多数广泛使用模型中嵌入的湍流封闭的改善，对气候和气候变化的研究。通过研究生的拟议参与给出了教育组成部分。