Low-Reynolds-number flow around an oscillating circular cylinder at low Keulegan-Carpenter numbers
Low-Reynolds-number flow around an oscillating circular cylinder at low Keulegan-Carpenter numbers
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DOI：
10.1017/s002211209800860x
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发表时间：
1998-04-10
影响因子：
3.7
通讯作者：
Lienhart, H
中科院分区：
文献类型：
--
作者：
Dutsch, H;Durst, F;Lienhart, H
采用时间平均LDA测量和时间分辨数值模拟方法，研究了静止状态下圆柱体在水中的简谐顺列振动引起的层流流动。改变关键参数雷诺数Re和Keulegan-Carpenter数Kc，对三种参数组合进行了详细的研究。当Re=100和Kc=5时，相平均速度矢量的测量值与预测值之间有很好的一致性。对于Re=200和Kc=10，出现了弱稳定和非周期流型，这使得可重复的时间平均测量变得不可能。然而，实验上可视化的涡旋动力学是通过二维计算再现的。对于第三种组合，Re=210和Kc=6，指的是完全不同的流型，计算再次导致正确的流体行为。应用Morison等人广泛使用的模型。(1950)对于计算的直列力历史，计算了不同网格水平和时间步长下的阻力系数和附加质量系数，并对其进行了比较。使用它们来复制力函数，可以发现与先前研究中已经注意到的原始计算结果的偏差。它们被发现比最粗略的计算网格或最大的时间步长的偏差要高得多。将几个内联力系数与Kuhtz(1996)在β=35时的实验结果进行比较，证实了力的预测也可以通过计算得到可靠的结果。
Time-averaged LDA measurements and time-resolved numerical flow predictions were performed to investigate the laminar flow induced by the harmonic in-line oscillation of a circular cylinder in water at rest. The key parameters, Reynolds number Re and Keulegan-Carpenter number KC, were varied to study three parameter combinations in detail. Good agreement was observed for Re = 100 and KC = 5 between measurements and predictions comparing phase-averaged velocity vectors. For Re = 200 and KC = 10 weakly stable and non-periodic flow patterns occurred, which made repeatable time-averaged measurements impossible. Nevertheless, the experimentally visualized vortex dynamics was reproduced by the two-dimensional computations. For the third combination, Re = 210 and KC = 6, which refers to a totally different flow regime, the computations again resulted in the correct fluid behaviour. Applying the widely used model of Morison et al. (1950) to the computed in-line force history, the drag and the added-mass coefficients were calculated and compared for different grid levels and time steps. Using these to reproduce the force functions revealed deviations from those originally computed as already noted in previous studies. They were found to be much higher than the deviations for the coarsest computational grid or the largest time step. The comparison of several inline force coefficients with results obtained experimentally by Kuhtz (1996) for beta = 35 confirmed that force predictions could also be reliably obtained by the computations.