Turbulent shear flow over active and passive porous surfaces
Turbulent shear flow over active and passive porous surfaces
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DOI：
10.1017/s0022112001004888
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发表时间：
2001-09-10
影响因子：
3.7
通讯作者：
Kawahara, G
中科院分区：
文献类型：
--
作者：
Jiménez, J;Uhlmann, M;Kawahara, G
本文用数值方法研究了质量中性透水壁面上剪切湍流的特性。蒸发被假定为与当地的压力波动成正比。它首先表明，摩擦系数增加了高达40%以上的被动多孔壁，即使是相对较小的孔隙率。这是与存在的大展向辊，起源于线性不稳定性，这是相关的Kelvin-Helmholtz不稳定性的剪切层，和中性无粘剪切波的平均湍流剖面。结果表明，辊可以被迫通过图案化的主动蒸腾通过壁，也导致摩擦的大幅增加时，强迫的相速度共振与上述线性特征函数。锁相平均的强制解决方案是用来进一步澄清的流动机制。本研究的动机是控制边界层中的分离。
The behaviour of turbulent shear flow over a mass-neutral permeable wall is studied numerically. The transpiration is assumed to be proportional to the local pressure fluctuations. It is first shown that the friction coefficient increases by up to 40% over passively porous walls, even for relatively small porosities. This is associated with the presence of large spanwise rollers, originating from a linear instability which is related both to the Kelvin-Helmholtz instability of shear layers, and to the neutral inviscid shear waves of the mean turbulent profile. It is shown that the rollers can be forced by patterned active transpiration through the wall, also leading to a large increase in friction when the phase velocity of the forcing resonates with the linear eigenfunctions mentioned above. Phase-lock averaging of the forced solutions is used to further clarify the flow mechanism. This study is motivated by the control of separation in boundary layers.