A simulation on bypass transition and its key mechanism
A simulation on bypass transition and its key mechanism
复制标题
旁路转换仿真及其关键机制
DOI：
10.1007/s11433-013-5036-2
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发表时间：
2013-03
期刊：
影响因子：
--
通讯作者：
董明
中科院分区：
文献类型：
--
作者：
董明
绕流转捩的理论描述一般是：自由流中的低频扰动在边界层中产生长的流向条纹，随后引起二次不稳定，导致高频扰动迅速增加，可能出现湍流斑，通过它们的合并，出现充分发展的湍流。然而，这种描述是不充分的，因为它没有解释为什么在破裂阶段，具有不同频率和波数的大量波几乎同时出现，导致平均流剖面的迅速变化。本文发现导致这一现象的机理是平均流廓线稳定性特征的变化，它对廓线本身的变化有正反馈作用。另一个有趣的发现是，在转捩过程中，首先出现的不稳定扰动波属于无粘模态的一个分支，而随着平均流剖面稳定性特征的变化，扰动波将转变为无粘模态的另一个分支，后者在旁路转捩中起着关键作用。
The scenario of bypass transition is generally described theoretically as follows: low-frequency disturbances in the free-stream would generate long stream-wise streaks in the boundary layer, which later would induce secondary instability, leading to rapid increase of high-frequency disturbances, then possibly turbulent spots would emerge, and through their merging, fully developed turbulence appears. This description, however, is insufficient in the sense that it does not provide the explanation on why during the breakdown stage, a large number of waves with different frequencies and wave numbers would appear almost simultaneously, leading to a swift change of the mean flow profile. In this paper, the mechanism leading to this phenomenon is found to be the change of the stability characteristics of mean flow profile, which has a positive feedback effect on the change of the profile itself. And another interesting finding is that, during the transition, the unstable disturbance waves which appear first belong to a branch of inviscid modes, while following the change of the stability characteristics of the mean flow profile, the disturbance waves will change to another branch of inviscid modes, and the latter play the key role in bypass transition.
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DOI：
10.1007/s11433-009-0162-6
发表时间：
2009-07
期刊：
Science in China Series G: Physics, Mechanics and Astronomy
影响因子：
--
作者：
Caihong Su;Heng Zhou
通讯作者：
Caihong Su;Heng Zhou
DOI：
10.2514/6.2011-3292
发表时间：
2011-06
期刊：
--
影响因子：
--
作者：
Yongmin Zhang;T. Zaki;S. Sherwin;Xuesong Wu
通讯作者：
Yongmin Zhang;T. Zaki;S. Sherwin;Xuesong Wu
影响因子：
4.6
作者：
D. Henningson
通讯作者：
D. Henningson
影响因子：
3.7
作者：
P. Ricco;Ji-sheng Luo;Xuesong Wu
通讯作者：
P. Ricco;Ji-sheng Luo;Xuesong Wu
影响因子：
4.6
作者：
P. Andersson;M. Berggren;D. Henningson
通讯作者：
P. Andersson;M. Berggren;D. Henningson