The flapping shear layer formed by flow separation from the forward corner of a square cylinder
The flapping shear layer formed by flow separation from the forward corner of a square cylinder
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DOI：
10.1017/s0022112094001217
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发表时间：
1994-05
影响因子：
3.7
通讯作者：
D. Lyn;W. Rodi
中科院分区：
文献类型：
--
作者：
D. Lyn;W. Rodi
本文用单分量激光多普勒测速仪研究了方柱前角分离流动在侧壁上形成的湍流剪切层及其回流区。由于涡的脱落，流动是近似周期性的，并被视为一个分离流受到大幅强迫在脱落频率。相（系综）平均速度和湍流强度，并在相位和振幅之间的密切关系的相位平均湍流强度和梯度的相位平均速度被发现在大部分的流动区域。研究了剪切层中相位平均剖面的相似性行为以及剪切层的流向增长。虽然相位平均速度分布崩溃以及在相似坐标，归一化湍流强度表现出系统的相似性偏差。剪切层的增长也明显偏离非强迫平面混合层的线性增长规律。再循环的效果建议作为一个可能的解释这些偏差。讨论了与定常和强制混合层、有再循环的定常分离流和非定常边界层的异同。
The turbulent shear layer and the associated recirculation region on the sidewall formed in flow separation from the forward corner of a square cylinder have been studied with one-component laser-Doppler velocimetry. Because of vortex shedding, the flow is approximately periodic, and is treated as a separated flow undergoing largeamplitude forcing at the shedding frequency. Phase (ensemble)-averaged velocities and turbulence intensities were obtained, and a close relationship in phase and amplitude between phase-averaged turbulence intensities and gradients of phase-averaged velocity is found in much of the flow region. The similarity behaviour of the phase-averaged profiles in the shear layer as well as the streamwise growth of the shear layer are investigated. While phase-averaged velocity profiles collapse well in similarity coordinates, normalized turbulence intensities exhibit systematic deviations from similarity. Shear-layer growth also departs markedly from the linear growth law of unforced plane mixing layers. The effect of the recirculation is suggested as a possible explanation for some of these deviations. Similarities to and differences from steady and forced mixing layers, steady separated flows with recirculation, and unsteady boundary layers are discussed.