Vortex Structure, Inverse Cascades, and Turbulent Bursts in Rotating, Stratified Flows

旋转层流中的涡流结构、逆级联和湍流爆发

• 批准号: 9978842
• 负责人: Philip Marcus
• 金额: $ 5万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-04-15 至 2001-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9978842&HistoricalAwards=false
• 关键词: Vortex; Structure; Inverse; Cascades; Turbulent

Three-dimensional simulations of fluid turbulence in rotating and stratified flows will be carried out using spectral methods using new efficient basis functions. The calculations will increase our understanding and ability to model and calculate turbulence in anisotropy and inhomogeneous settings that are commonly found in geophysical and astrophysical flows and is many engineering applications. Rotation and stratification tend to make the fluid act nearly 2-dimensional (2D) at some locations, at some length scales, and/or for some intervals of time. It is commonly thought that when and where the flows behave as if they were fully 3D, energy is transferred ("forward cascades") from large to small scales, and small-scale turbulence acts primarily as a passive "sponge" dissipating energy. When and where the flows behave as if it were 2D, energy inverse cascades from small to large scales. In these cases the small-scale turbulence is much more complex and difficult to model, and its effects on the large-scales are more profound. A mathematical model of the inverse cascade will be developed and scaling laws for the strengths and widths of planetary jet streams will be developed and compared against simulations, experiments and observations. Asymptotics, and mathematical models for the turbulence will permit construction of new sub-grid-scale turbulence models to be used in large-eddy numerical simulations. The simulations will be compared to laboratory experiments and observations and observations of geophysical and astrophysical flows.The specific features of this investigation place it outside of the norm for most studies of turbulent/vortical motions. It is expected that the distinct results to be obtained will not only serve to illuminate the "2-D" turbulence problem but also the more general turbulent flow processes by noting the similarities/differences between the two.

将使用新的有效基础函数的光谱方法进行旋转和分层流中流体湍流的三维模拟。 计算将提高我们在各向异性和不均匀环境中建模和计算湍流建模和计算湍流的能力，这些环境通常在地球物理和天体物理流中发现，并且是许多工程应用。 旋转和分层倾向于在某些位置，一定程度和/或一定时间间隔使流体作用在某些位置几乎二维（2D）。 人们通常认为，流动的行为何时何地表现，好像它们是完全3D，能量被转移（“正向级联”）从大型到小尺度，而小规模的湍流主要用作被动的“海绵”消散能量。 何时何地，流动的行为就像是2D，能量从小到大尺度的级联反向级联反应。 在这些情况下，小规模的湍流要复杂得多且难以建模，并且其对大型的影响更加深刻。 将开发逆级联的数学模型，并将开发针对行星喷射流的强度和宽度的缩放定律，并与模拟，实验和观测值进行比较。 湍流的渐近学和数学模型将允许在大型数值模拟中使用新的子网格尺度湍流模型。 将将模拟与实验室实验，观察和观察到地球物理和天体物理流的观察结果进行比较。这项研究的特定特征使其超出了大多数湍流/涡流运动研究的规范。 可以预期，要获得的明显结果不仅可以通过指出两者之间的相似性/差异来阐明“ 2-D”湍流问题，而且还可以阐明更通用的湍流流程。