Collaborative Research: Self-organization and transitions in anisotropic turbulence

合作研究：各向异性湍流的自组织和转变

• 批准号: 2308338
• 负责人: Keith Julien
• 金额: $ 18.7万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-01 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2308338&HistoricalAwards=false
• 关键词: Collaborative; Research; Self; organization; transitions

The impact of rotation and thermal driving on stellar and planetary bodies is clearly visible in far-field optical observations. Such observations reveal the presence of differentially rotating fluid atmospheres with embedded features in the form of large-scale eddies and jets that greatly influence the climate on the celestial body. On Earth the impact of the high latitude jet stream on weather and the destructive impact of hurricanes due to climate change is evident. Within the Jovian atmosphere, the recent discovery by the Juno mission of polar vortices illuminates the longevity of vortical structures. Theory, experimentation, and numerical simulations strongly suggest that the generation of large-scale jets and vortices is common in fluid turbulence within thin layers like the Earth’s atmosphere and on rapidly rotating celestial bodies such as Jupiter. Focusing on these paradigms, this project is dedicated to elucidating the basic mechanism behind the formation of such large-scale structures from small-scale turbulent fluctuations and its disruption via the generation of isolated, weakly-interacting, mesoscale shielded vortices, and to extending this understanding to more realistic models that introduce higher level physics such as the effects of water vapor and internal heating via latent heat release. This understanding will inform more detailed studies such as those based on realistic Global Ocean and Atmospheric Circulation Models and offers hope for understanding the conditions favoring the formation of both large-scale structures and of the smaller-scale shielded vortices. The modeling strategy taken provides a foundation upon which greater discipline-specific complexity can be built. The project will support and train one graduate student and one postdoctoral researcher in the physical understanding of energy transfer between scales in systems of geophysical relevance, asymptotic and other modeling techniques, as well as direct numerical simulations of rapidly rotating fluid layers, appropriate for planetary-scale phenomena on and within the Earth.The aim of this project is to classify different regimes of instability-driven turbulence in two dimensions (2D) as a function of the energy input and dissipation parameters, and to explore how these states evolve when three-dimensional (3D) fluctuations become increasingly important as the height of the turbulent layer increases. Particular emphasis will be placed on the recently discovered regime of shielded mesoscale vortices whose generation may disrupt the inverse energy cascade familiar from 2D turbulence with random stirring. Properties of the resulting chiral mesoscale vortex gas will be studied as a function of the layer height, as will the transition to a vortex crystal that takes place at high vortex density in 2D. The Reynolds number will be varied systematically to bridge the gap between these phenomena and related states in bacterial suspensions at low Reynolds numbers. The possibility of an analogous state in rapidly rotating 3D turbulence will be investigated in detail using a new reformulation of the Navier-Stokes fluid equations, extending direct numerical simulations to smaller Rossby numbers, together with a theoretical analysis dissecting the amplitude-phase relationships between large-scale structures and small-scale turbulence.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

在远场光学观测中，旋转和热驱动对恒星和行星体的影响清晰可见。这样的观察结果揭示了具有不同旋转的流体气氛，具有嵌入式特征的大规模涡形和喷气式的形式，这些特征很大程度上影响了气候对天体的影响。在地球上，高纬度喷气流对天气以及由于气候变化引起的飓风的破坏性影响。在Jovian的气氛中，朱诺（Juno）的最近发现极地涡流的发现阐明了涡流结构的寿命。理论，实验和数值模拟强烈表明，大规模喷射和涡流的产生在薄层（例如地球大气层）和迅速旋转的天体（如木星）中很常见。该项目着重于这些范式，致力于阐明从小规模的湍流波动形成这种大规模结构的基本机制，并通过产生孤立的，弱相互关联的，中尺度上的中尺度上的涡流涡流，以及将这种理解范围扩展到更现实的热量中，从而通过较高的级别的物理学来延伸效应效果和效果。这种理解将为更详细的研究提供信息，例如基于现实的全球海洋和大气循环模型，并为了解有利于形成大型结构和较小规模屏蔽涡流形成的条件提供了希望。建模策略为基础提供了一个基础，可以建立更大的纪律特定复杂性。该项目将支持并培训一名研究生和一名博士后研究人员对地球物理相关性，不对称和其他建模技术的量表之间的能量转移的物理理解，以及迅速旋转流体层的直接数值，适用于地球上和两次diffife the Instancie the Instancie the Instancime and the Instancime and drowd drard turn the Instancime and the Instancime and the Instable（与Instable）的构图（能量输入和耗散参数的函数，并探讨当三维（3D）波动随着湍流层的高度增加而变得越来越重要时，这些状态如何发展。特别重点将放在最近发现的屏蔽中尺度涡旋的方向上，其产生可能会破坏因2D湍流而随机搅拌而熟悉的反向能量级联反应。所产生的手性中尺度涡流气体的性能将作为层高度的函数进行研究，以及在2D中高涡流密度以高涡流密度发生的涡流晶体的函数。雷诺数将系统地变化，以弥合雷诺数低的细菌悬浮液中这些现象和相关状态之间的差距。快速旋转3D湍流中类似状态的可能性将通过对Navier-Stokers流体方程式进行新的改革进行详细研究，将直接数值模拟扩展到较小的Rossby数字，并通过理论分析解析了通过对大规模结构和小规模的湍流之间的支持，将放大器 - 相位的关系解剖，并在较小的湍流中进行了支持。基金会的智力优点和更广泛的影响审查标准。