CAREER: Towards understanding and modeling Turbulent Buoyant Flows

职业：理解和模拟湍流浮力流

• 批准号: 1056142
• 负责人: Guillaume Blanquart
• 金额: $ 40万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-03-01 至 2016-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1056142&HistoricalAwards=false
• 关键词: CAREER; Towards; understanding; modeling; Turbulent

1056142 Blanquart Rayleigh-Taylor instabilities appear when a heavy fluid is placed on top of a light fluid. The light fluid rises as a result of buoyancy forces, and in many cases, the flow transitions rapidly to turbulence. Due to their intrinsic nature, Rayleigh-Taylor instabilities are found in a large diversity of engineering applications and natural phenomena (inertial confinement fusion, furnaces, accidental fires, heat transfer within stars, supernova formation, underwater hot vents, oil spill). A lot of work has been done on the initial and long term growth of Rayleigh-Taylor instabilities. However, little is known about the structure of the turbulence inside buoyant mixing layers. A perfect example is the observed anisotropy of scales in direct contradiction with the well established Kolmogorov theory and which remains currently unexplained by any theoretical models. In order to gain access to the fine details of turbulence, Direct Numerical Simulations of various "con-trolled experiments" will be performed. These configurations span all regimes of turbulent buoyant flows, from weak buoyancy to buoyancy-dominated turbulence. The data will be used to analyze the growth of Rayleigh-Taylor instabilities, the emergence of scale anisotropy in buoyant flows, and the effects of Richardson and Atwood numbers. The outcome is multiple and includes the formulation of a novel theoretical framework unifying turbulent non-buoyant and buoyant flows. This first-of-a-kind model will correlate the anisotropy of scales and the energy spectra to the Richardson number of the turbulent structures. The project will result also in the development of new subgrid scale models specifically designed for Large Eddy Simulations of turbulent buoyant flows. This research project is integrated closely with an educational plan. Three key tasks have been chosen, and each task is targeting a real social problem. This includes performing hands-on experiments in middle school at a time when students lose interest in science. This includes engaging undergraduate students in research projects and providing them with the knowledge and skills to continue to graduate school. Finally, this includes reaching out to the general public to ensure that our work does not remain unknown. In addition, the research plan will ensure scientists across disciplines (engineering and non-engineering) benefit directly from the research project. In addition to establishing passive means of exchanging data, explicit collaborations have been initiated with personnel in other universities and national laboratories.

1056142 当重流体置于轻流体之上时，会出现 Blancquart Rayleigh-Taylor 不稳定性。轻质流体由于浮力而上升，并且在许多情况下，流动迅速转变为湍流。由于其固有的性质，瑞利-泰勒不稳定性存在于各种各样的工程应用和自然现象中（惯性约束聚变、熔炉、意外火灾、恒星内的传热、超新星形成、水下热喷口、石油泄漏）。关于瑞利-泰勒不稳定性的初始和长期增长已经做了很多工作。然而，人们对浮力混合层内部湍流的结构知之甚少。一个完美的例子是观察到的尺度各向异性，它与完善的柯尔莫哥洛夫理论直接矛盾，并且目前仍然无法用任何理论模型来解释。为了获得湍流的细节，将对各种“受控实验”进行直接数值模拟。这些配置涵盖了所有湍流浮力流状态，从弱浮力到浮力主导的湍流。这些数据将用于分析瑞利-泰勒不稳定性的增长、浮力流中尺度各向异性的出现以及理查森和阿特伍德数的影响。结果是多种多样的，包括制定统一湍流非浮力流和浮力流的新颖理论框架。这个史无前例的模型将尺度各向异性和能谱与湍流结构的理查森数相关联。该项目还将开发专门用于湍流浮力流大涡流模拟的新子网格比例模型。该研究项目与教育计划紧密结合。我们选择了三个重点任务，每个任务都针对一个现实的社会问题。这包括在中学时学生对科学失去兴趣时进行动手实验。这包括让本科生参与研究项目，并为他们提供继续读研究生的知识和技能。最后，这包括接触公众，以确保我们的工作不会仍然无人知晓。此外，该研究计划将确保跨学科（工程和非工程）的科学家直接从研究项目中受益。除了建立被动的数据交换方式外，还与其他大学和国家实验室的人员开展了明确的合作。