On a self-sustaining process in shear flows
On a self-sustaining process in shear flows
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DOI：
10.1063/1.869185
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发表时间：
1997-04-01
影响因子：
4.6
通讯作者：
Waleffe, F
中科院分区：
文献类型：
--
作者：
Waleffe, F
本文研究了壁面剪切流的一个自维持过程。自持过程由流向辊组成，流向辊重新分配平均剪切力以产生摆动以维持辊的条纹。该过程进行了分析，并示出是显着不敏感，是否有无滑移或自由滑移的墙壁。从正弦剪切流的Navier-Stokes方程推导出该过程的低阶模型。该模型有两个不稳定的稳定的解决方案，在临界雷诺数以上，除了稳定的层流。对于某些参数值，存在第二临界雷诺数，在该临界雷诺数下，同宿分支产生稳定的周期解。这表明了不稳定的稳定的解决方案和几乎周期的解决方案，已计算在平面库埃特流之间的直接联系。IL认为，这种自我维持的过程是负责在低雷诺数的剪切流的分叉，也许也为控制近壁区的湍流剪切流在较高的雷诺数。(C)1997年美国物理学会。
A self-sustaining process conjectured to be generic for wall-bounded shear flows is investigated. The self-sustaining process consists of streamwise rolls that redistribute the mean shear to create streaks that wiggle to maintain the rolls. The process is analyzed and shown to be remarkably insensitive to whether there is no-slip or free-slip at the walls. A low-order model of the process is derived from the Navier-Stokes equations for a sinusoidal shear flow. The model has two unstable steady solutions above a critical Reynolds number, in addition to the stable laminar flow. For some parameter values, there is a second critical Reynolds number at which a homoclinic bifurcation gives rise to a stable periodic solution. This suggests a direct link between unstable steady solutions and almost periodic solutions that have been computed in plane Couette flow. IL is argued that this self-sustaining process is responsible for the bifurcation of shear flows at low Reynolds numbers and perhaps also for controlling the near-wall region of turbulent shear flows at higher Reynolds numbers. (C) 1997 American Institute of Physics.