Induced flow due to blowing and suction flow control: an analysis of transpiration
Induced flow due to blowing and suction flow control: an analysis of transpiration
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吹气和吸气流量控制引起的诱导流：蒸腾作用分析
DOI：
10.1017/jfm.2011.441
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发表时间：
2011
影响因子：
3.7
通讯作者：
I. Marusic
中科院分区：
文献类型：
--
作者：
J. Woodcock;J. Sader;I. Marusic
以前已经证明，通过使通道壁处的流动受到吹吸的动态状态(也称为蒸腾)，可以减小通道中的泊松叶流所经历的阻力。此外，人们已经发现，仅通过蒸腾作用就可以在通道中诱导“大块流动”或稳定的运动。在这项工作中，我们通过摄动分析得到了诱导体流的显式渐近表达式。由此，我们可以洞察流动中起作用的物理机制。所用的边界条件是任意一面墙上的行波，其幅度和相位可能不同。文中论证了诱导体流是对流作用的结果。我们发现，诱导体流的最有效的布置是两边的边界条件大小相等而符号相反的布置。我们还证明，对于不可忽略的体流，边界条件的波长应该与通道高度相当或大于通道高度。此外，我们还导出了在这种边界条件下使诱导体流最大的最优振荡频率。在结论中详细描述了体流的渐近行为。研究发现，在一定的条件下，如果边界条件的幅值太大，诱导的体流将只依赖于边界条件沿渠道壁面移动的速度。我们提出的猜想是，对于所有相似的流动，如果蒸腾的大小足够大，整体流动将只取决于边界条件的速度。
Abstract It has previously been demonstrated that the drag experienced by a Poiseuille flow in a channel can be reduced by subjecting the flow to a dynamic regime of blowing and suction at the walls of the channel (also known as ‘transpiration’). Furthermore, it has been found to be possible to induce a ‘bulk flow’, or steady motion through the channel, via transpiration alone. In this work, we derive explicit asymptotic expressions for the induced bulk flow via a perturbation analysis. From this we gain insight into the physical mechanisms at work within the flow. The boundary conditions used are of travelling sine waves at either wall, which may differ in amplitude and phase. Here it is demonstrated that the induced bulk flow results from the effect of convection. We find that the most effective arrangement for inducing a bulk flow is that in which the boundary conditions at either wall are equal in magnitude and opposite in sign. We also show that, for the bulk flow induced to be non-negligible, the wavelength of the boundary condition should be comparable to, or greater than, the height of the channel. Moreover, we derive the optimal frequency of oscillation, for maximising the induced bulk flow, under such boundary conditions. The asymptotic behaviour of the bulk flow is detailed within the conclusion. It is found, under certain caveats, that if the amplitude of the boundary condition is too great, the bulk flow induced will become dependent only upon the speed at which the boundary condition travels along the walls of the channel. We propose the conjecture that for all similar flows, if the magnitude of the transpiration is sufficiently great, the bulk flow will depend only upon the speed of the boundary condition.
影响因子：
3.7
作者：
R. Whittaker;M. Heil;J. Boyle;O. Jensen;S. Waters
通讯作者：
R. Whittaker;M. Heil;J. Boyle;O. Jensen;S. Waters
影响因子：
3.7
作者：
R. Whittaker;S. Waters;O. Jensen;J. Boyle;M. Heil
通讯作者：
R. Whittaker;S. Waters;O. Jensen;J. Boyle;M. Heil