Importance of small-scale anisotropy in the turbulent/nonturbulent interface region of turbulent free shear flows
Importance of small-scale anisotropy in the turbulent/nonturbulent interface region of turbulent free shear flows
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湍流自由剪切流的湍流/非湍流界面区域中小尺度各向异性的重要性
DOI：
10.1103/physrevfluids.4.034603
复制
发表时间：
2019
影响因子：
2.7
通讯作者：
Buxton O
中科院分区：
文献类型：
--
作者：
Buxton O
在过去的十多年里，关于湍流/非湍流（TNT）界面厚度的标度问题一直存在很多争论。一般认为它由粘性过程重要的外部粘性超层和以惯性过程为主的内部湍流亚层组成。许多作者都认为界面厚度与泰勒长度尺度有关，而另一些人则认为它与柯尔莫哥洛夫长度尺度有关[Buxton， Phys]。[j].中国生物医学工程学报，2011,32(4):555 - 556。通常，只考虑自相似的湍流，其中任意一个值足以衡量各种现象，包括TNT界面的厚度。在本文中，我们证明了对于非自相似的流动，局部Kolmogorov长度尺度随着靠近湍流和非湍流之间的边界而显著增加。我们发现该局部Kolmogorov长度尺度随距离TNT边界法向距离的变化可以用TNT边界本身计算的局部Kolmogorov长度尺度来坍缩。我们随后表明，这种局部Kolmogorov长度尺度的变化与TNT界面中小尺度各向异性的增加同时发生。这种各向异性在粘性超层和湍流亚层之间的边界处达到顶峰，这表明这两个亚层实际上是截然不同的。我们表明，这些结果适用于来自不同流动的许多不同的TNT界面，以及处于各种发展状态的大块湍流。我们得到的局部粘性标度，以及主要由TNT边界法向速度梯度的增加所引起的各向异性的增加，使我们将TNT界面与壁面有界湍流中的壁面进行了类比。
There has been much debate over the past decade or so over the scaling of the thickness of the turbulent/nonturbulent (TNT) interface for turbulent shear flows. It is generally considered to consist of the outer viscous superlayer, in which viscous processes are significant, and an inner turbulent sublayer which is dominated by inertial processes. Various authors have stated that the interface thickness scales with the Taylor length scalewhile others state that it scales with the Kolmogorov length scale[Buxton , Phys. Fluids 23, 061704 (2011)PHFLE61070-663110.1063/1.3599080]. Frequently, only self-similar turbulent flows are considered in which a single value of eitheroris sufficient to scale various phenomena, including the thickness of the TNT interface. In this paper we show that for flows which are not self-similar the local Kolmogorov length scale increases quite significantly as one moves closer to the boundary between the turbulent and nonturbulent fluid. We find that the variation of this local Kolmogorov length scale with normal distance from the TNT boundary may be collapsed by the local Kolmogorov length scale computed from the TNT boundary itself. We subsequently show that this variation in local Kolmogorov length scale occurs concurrently with an increase in the small-scale anisotropy in the TNT interface. This anisotropy peaks at the boundary between the viscous superlayer and the turbulent sublayer, suggesting that these two sublayers are in fact quite distinct from one another. We show that these results hold for a number of different TNT interfaces from various flows and with the bulk turbulence being in a variety of states of development. The local viscous scaling that we obtain, along with an increase in anisotropy primarily driven by an increased magnitude of velocity gradients in the TNT-boundary-normal direction, leads us to draw an analogy between TNT interfaces and the wall in wall-bounded turbulence.
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影响因子：
3.7
作者：
Tiago S. Silva;Marco Zecchetto;C. B. da Silva
通讯作者：
Tiago S. Silva;Marco Zecchetto;C. B. da Silva
影响因子：
8.6
作者：
M. Holzner;B. Lüthi
通讯作者：
M. Holzner;B. Lüthi
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
具有湍流/非湍流界面的无剪切流中的谱熵预算
DOI：
--
发表时间：
2015
期刊：
影响因子：
--
作者：
A. Cimarelli;G. Cocconi;B. Frohnapfel;E. Angelis
通讯作者：
E. Angelis
近壁湍流的柯尔莫哥洛夫行为及其在湍流建模中的应用
DOI：
--
发表时间：
1992
期刊：
影响因子：
--
作者：
T. Shih;J. Lumley
通讯作者：
J. Lumley