Spiral structures in turbulent flow
Spiral structures in turbulent flow
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湍流中的螺旋结构
DOI：
10.1007/978-3-0348-8585-0_8
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
H. K. Moffatt
中科院分区：
文献类型：
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作者：
H. K. Moffatt
螺旋结构是湍流“类属结构”的自然候选者，因为它们是开尔文-亥姆霍兹不稳定性的最终结果，开尔文-亥姆霍兹不稳定性是一种普遍存在的现象，几乎所有的剪切流都与非常高的雷诺数有关。这种结构是由Lundgren(1982)在湍流精细结构模型中提出的，其中卷起的螺旋涡的轴向拉伸起着重要的作用。这个模型可以看作是Townsen(1951)湍流耗散结构模型的自然发展，该模型是根据涡片和/或涡管的随机分布来建立的，每个涡片和/或涡管都受到与所有其他涡旋结构(见Batchelor 1982，§)相关的局部应变率(假设为均匀和恒定)的影响(见Batchelor 1982，§已知压缩应变(具有两个正的主应变速率)在各向同性湍流中比广泛应变更有可能)，因此形成涡片的概率比涡管更高。然而，它们立即受到开尔文-亥姆霍兹不稳定性的影响，这种不稳定性可能会被拉伸过程阻止，但不会完全被抑制。
Spiral structures are natural candidates for the role of the ‘generic structures’ of turbulent flow, because they are the eventual outcome of Kelvin-Helmholtz instability, an all-pervasive phenomenon associated with nearly all shear flows at very high Reynolds number. Such structures were proposed by Lundgren (1982) in a model of the fine structure of turbulence in which axial stretching of rolled-up spiral vortices played an essential role. This model could be viewed as a natural development of Townsend’s (1951) model of the dissipative structures of turbulence in terms of a random distribution of vortex sheets and/or tubes, each such structure being subjected to the local rate of strain (assumed uniform and constant) associated with all other vortex structures (see Batchelor 1982, § is known that compressive strain (with two positive principle rates of strain) is more likely in isotropic turbulence than extensive strain, so that sheets form with higher probability than tubes. However these are immediately subject to the Kelvin-Helmholtz instability which may be impeded, but not entirely suppressed, by the stretching process.