Modulation of the velocity gradient tensor by concurrent large-scale velocity fluctuations in a turbulent mixing layer
Modulation of the velocity gradient tensor by concurrent large-scale velocity fluctuations in a turbulent mixing layer
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湍流混合层中同时发生的大规模速度波动对速度梯度张量的调制
DOI：
10.1017/jfm.2015.357
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发表时间：
2015
影响因子：
3.7
通讯作者：
Buxton O
中科院分区：
文献类型：
--
作者：
Buxton O
在考虑Kullback-Leibler散度的情况下，观测到同时存在的大尺度速度涨落对小尺度速度和速度梯度量的调制。这是一种量度，用来量化在模拟以同时的大范围正波动为条件的小规模量的统计分布时的信息损失，而不是以大范围的负波动为条件的小规模量的统计分布。在充分发展的湍流混合层的低速侧，当大尺度脉动为正值时，小尺度湍流明显变得“粗糙”，这进一步证明了Buxton和Ganapathisubramani(Phys)的对流尺度调制论点。《流体》，第26卷，2014年，125106，1-19)。小尺度的定义是不同的，无论小尺度涨落是以耗散为主还是具有惯性范围湍流的特征，都表现为同时存在的大尺度涨落的调制。即使在小尺度和大尺度之间的波数空间中有很大的差距时，也观察到调制持续存在，尽管在显著大于预定义小尺度的中间长度尺度上观察到局部极大值。最后，观察到小尺度耗散的调制大于拟能的调制，而涡旋伸展项的调制介于两者之间，表明了应变率和旋转率之间的相互作用。
The modulation of small-scale velocity and velocity gradient quantities by concurrent large-scale velocity fluctuations is observed by consideration of the Kullback–Leibler divergence. This is a measure that quantifies the loss of information in modelling a statistical distribution of small-scale quantities conditioned on concurrent positive large-scale fluctuations by that conditioned on negative large-scale fluctuations. It is observed that the small-scale turbulence is appreciably ‘rougher’ when the concurrent large-scale fluctuation is positive in the low-speed side of a fully developed turbulent mixing layer, which gives further evidence to the convective scale modulation argument of Buxton & Ganapathisubramani (Phys. Fluids, vol. 26, 2014, 125106, 1–19). The definition of the small scales is varied, and regardless of whether the small-scale fluctuations are dominated by dissipation or have the characteristic features of inertial range turbulence they are shown to be modulated by the concurrent large-scale fluctuations. The modulation is observed to persist even when there is a large gap in wavenumber space between the small and large scales, although local maxima are observed at intermediate length scales that are significantly larger than the predefined small scales. Finally, it is observed that the modulation of small-scale dissipation is greater than that for enstrophy with the modulation of the vortex stretching term, indicative of the interaction between strain rate and rotation, being intermediate between the two.
从惯性范围到耗散长度尺度的剪切流湍流中应变率和旋转之间的相互作用
影响因子：
4.6
作者：
Buxton O
通讯作者：
Buxton O
影响因子：
3.7
作者：
Buxton, O. R. H.;Ganapathisubramani, B.
通讯作者：
Ganapathisubramani, B.
影响因子：
3.7
作者：
Mathis, Romain;Marusic, Ivan;Hutchins, Nicholas
通讯作者：
Hutchins, Nicholas