The autonomous cycle of near-wall turbulence
The autonomous cycle of near-wall turbulence
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DOI：
10.1017/s0022112099005066
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发表时间：
1999-06-25
影响因子：
3.7
通讯作者：
Pinelli, A
中科院分区：
文献类型：
--
作者：
Jiménez, J;Pinelli, A
在中等雷诺数的修正湍流通道上进行了数值实验，以区分壁面边界流中湍流脉动的几种可能的再生循环。结果表明，在近壁区存在一个与外部流动无关的局部循环。它包括由流向涡对平均廓线的平流形成的速度条纹，以及由条纹的不稳定性产生的涡。中断这些过程中的任何一个都会导致分层。墙的存在似乎只是维持平均剪切力所必需的。结果表明，在自然条件下，壁面二次涡量的产生对湍流的产生并不重要。抑制其产生会增加湍流强度和阻力。
Numerical experiments on modified turbulent channels at moderate Reynolds numbers are used to differentiate between several possible regeneration cycles for the turbulent fluctuations in wall-bounded flows. It is shown that a cycle exists which is local to the near-wall region and does not depend on the outer flow. It involves the formation of velocity streaks from the advection of the mean profile by streamwise vortices, and the generation of the vortices from the instability of the streaks. Interrupting any of those processes leads to laminarization. The presence of the wall seems to be only necessary to maintain the mean shear. The generation of secondary vorticity at the wall is shown to be of little importance in turbulence generation under natural circumstances. Inhibiting its production increases turbulence intensity and drag.