| 项目编号: | 1706950
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| 项目名称: | Geometric Structure of the Turbulent Cascade |
| 作者: | Nicholas Ouellette
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| 承担单位: | Stanford University
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| 批准年: | 2017
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| 开始日期: | 2017-09-01
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| 结束日期: | 2020-08-31
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| 资助金额: | 336975
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| 资助来源: | US-NSF
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| 项目类别: | Standard Grant
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| 国家: | US
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| 语种: | 英语
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| 特色学科分类: | Engineering - Chemical, Bioengineering, Environmental, and Transport Systems
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| 英文关键词: | research
; turbulent cascade
; result
; detailed structure
; characteristic cascade
; turbulent energy cascade
; alignment
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| 英文摘要: | The majority of fluid flows in nature and in engineering applications are turbulent. But despite being so commonplace, understanding and modeling turbulence remains a significant challenge. Turbulent flows are distinct from more general unsteady flows because they display a characteristic cascade of energy from the large length scales at which energy is generated to the small length scales on which it is dissipated by viscosity. Typically, this process is described in an abstract way that makes it difficult to appreciate the underlying physics. The goal of this proposed research is to recast the turbulent energy cascade as a mechanical process, where large scales do work on the small scales. This model immediately emphasizes the important role played by geometry, since if the forces provided by the large scales are misaligned with the flow direction, they can do no work. In this proposed research, the geometry of the turbulent cascade will be studied in detail and its links to other turbulent processes will be clarified. Ultimately, the results of this research may lead to new strategies for turbulence modeling. The proposed research will support the education and training of graduate students, and the results will be folded into existing graduate courses. Additionally, the supported scientists will participate in educational outreach activities coordinate through Stanford's Bob and Norma Street Environmental Fluid Mechanics Laboratory.
The objective of this proposed research is to gain a deeper understanding of how the geometric properties of scale-dependent turbulent stresses and strain rates and, in particular, their relative alignment control the turbulent cascade. Specifically, the alignment and possible spatial ordering of the turbulent stress and strain rate will be characterized, an understanding of how this alignment is modulated by advection will be developed, and potential links between alignment and intermittency will be investigated. These questions will be studied via theoretical work and analysis of data sets for three-dimensional turbulence, two-dimensional turbulence, and unsteady, random, and multiscale but non-turbulent velocity fields. By basing this research on sound and transparent mechanical principles of work and energy transfer, the results will bring new clarity to the origins of the detailed structure of turbulence that is more interpretable than abstract approaches such as multifractality. |
| 资源类型: | 项目
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/89110
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| Appears in Collections: | 全球变化的国际研究计划
科学计划与规划
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| Recommended Citation: | |
Nicholas Ouellette. Geometric Structure of the Turbulent Cascade. 2017-01-01.
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