Simulation and Modeling of the Decay of Anisotropic Turbulence

各向异性湍流衰减的模拟和建模

• 批准号: 1032364
• 负责人: Blair Perot
• 金额: $ 27.21万
• 依托单位: University of Massachusetts Amherst
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1032364&HistoricalAwards=false
• 关键词: Simulation; Modeling; Decay; Anisotropic; Turbulence

A very large number of industrial and environmental processes involve fluids whose motion is turbulent. This project involves the accurate statistical prediction and modeling of these chaotic, unsteady, and three-dimensional fluid motions. The focus is on simulating and then modeling the turbulent return-to-isotropy process which has resisted modeling efforts in the past.The return-to-isotropy process significantly influences near wall turbulence, duct flows, atmospheric and oceanic heat and mass transfer processes like CO2 absorption, heat exchanger performance, wing tip vortices, and a host of important and currently poorly modeled turbulent flow situations. Information about the structure (i.e. the shape of the underlying eddies) is hypothesized to control the return-to-isotropy process. In order to determine the contribution due to structure, large domain direct numerical simulations (DNS) of return-to-isotropy in homogeneous anisotropic turbulence are performed. Anisotropy is generated by five fundamentally different mean strains and by walls. Each produces very different turbulent structures. The influence on the return-to-isotropy process of the Reynolds number, initial length scale, and initial structure (parameterized by the two-point correlations) will be characterized and used to calibrate the oriented-eddy turbulence model. The oriented-eddy collision model is implemented in the open source CFD program, OpenFoam making it easily available to the scientific community. This open source implementation will allow others to rapidly test the accuracy of the model in any complex configuration of their choosing. Intellectual Merit: This work will significantly enhance our current understanding of how turbulence structure influences its nonlinear evolution. It is anticipated that the oriented-eddy collision model will be the first turbulence model capable of predicting the return-to-isotropy process accurately for a wide variety of different scenarios. In addition, this work will provide critical information for other turbulence models which incorporate turbulence structure. Broader Impacts: Turbulence models are a necessary component of most computational fluid dynamics (CFD) simulations. Models with quantitative predictive accuracy could radically transform the utility of CFD as a design and prediction tool. This project will provide researchers in this field with a high quality database consisting of canonical turbulent flows. Some of the supercomputing tasks in this project can, and will, be performed by undergraduate researchers during summer REU experiences that target women and minorities. This work will be disseminated to the general public via WFCR, our local public radio affiliate.

大量的工业和环境过程都涉及湍流运动的流体。该项目涉及对这些混沌、非定常和三维流体运动进行精确的统计预测和建模。重点是对紊流回归各向同性过程进行模拟和建模，这一过程在过去一直受到建模努力的阻碍。回归各向同性过程显著影响近壁湍流、风道流动、大气和海洋传热传质过程，如CO2吸收、热交换器性能、翼尖涡，以及一系列重要的、目前尚未建立模型的湍流情况。有关结构的信息（即底层涡流的形状）被假设为控制返回各向同性的过程。为了确定结构的贡献，进行了均匀各向异性湍流中回归各向同性的大域直接数值模拟。各向异性是由五种基本不同的平均应变和壁面产生的。每一种都会产生非常不同的湍流结构。雷诺数、初始长度尺度和初始结构（由两点相关参数化）对回归各向同性过程的影响将被表征并用于校准定向涡湍流模型。定向涡流碰撞模型是在开源CFD程序中实现的，OpenFoam使其易于科学界使用。这个开源实现将允许其他人在他们选择的任何复杂配置中快速测试模型的准确性。知识价值：这项工作将大大提高我们目前对湍流结构如何影响其非线性演化的理解。预计定向涡碰撞模型将是第一个能够准确预测各种不同情景下的回归各向同性过程的湍流模型。此外，这项工作将为其他包含湍流结构的湍流模型提供关键信息。更广泛的影响：湍流模型是大多数计算流体动力学（CFD）模拟的必要组成部分。具有定量预测精度的模型可以从根本上改变CFD作为设计和预测工具的效用。该项目将为该领域的研究人员提供一个高质量的典型湍流数据库。这个项目中的一些超级计算任务可以，也将由本科研究人员在夏季的REU体验中执行，目标是女性和少数族裔。这项工作将通过我们当地的公共广播电台WFCR向公众传播。