Dynamics of vortex lock-on in a perturbed cylinder wake
Dynamics of vortex lock-on in a perturbed cylinder wake
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DOI：
10.1063/1.2221350
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发表时间：
2006-07
影响因子：
4.6
通讯作者：
Wontae Kim;J. Yoo;J. Sung
中科院分区：
文献类型：
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作者：
Wontae Kim;J. Yoo;J. Sung
应用雷诺数为360的时间分辨粒子图像测速技术，研究了非零平均速度振荡流动中圆柱体下游的旋涡锁定动力学。由于柱体后的近尾迹受到两倍于自然脱落频率的扰动而发生锁定，我们询问了平均回流和涡形成的尾迹区，并分析了脱落涡的动力学行为、相干结构、涡旋演化的阶段和雷诺应力场。结果表明，由于旋涡的锁定，平均回流区和旋涡形成区显著减少，这与前人的研究结果一致。此外，近尾迹动能更多地集中在圆柱体底部附近。基于复特征值和涡心的混合方法计算得到的落叶涡轨迹发生了显著的变化。提出了一种新的相态识别方法，并在此基础上提出了一种新的相分离方法。
The dynamics of vortex lock-on, downstream of a circular cylinder in an oscillatory flow with nonzero mean velocity, is investigated by applying a time-resolved particle image velocimetry technique at the Reynolds number 360. Since the lock-on occurs when the near wake behind a cylinder is perturbed at twice the natural shedding frequency, we interrogate the wake regions of mean recirculation and vortex formation, and analyze the dynamic behavior of the shed vortices, the coherent structure, the phases of vortex evolution, and the Reynolds stress fields. It is shown that due to vortex lock-on the mean recirculation and vortex formation regions are considerably reduced, which is consistent with previous studies. Besides, the kinetic energy in the near wake is more concentrated near the cylinder base. A dramatic change is demonstrated in the trajectory of the shed vortices, which is evaluated from a hybrid method based on complex eigenvalue and vortex centroid. A novel method to identify the phases of the v...