Effect of blockage on free vibration of a circular cylinder at low Re
Effect of blockage on free vibration of a circular cylinder at low Re
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DOI：
10.1002/fld.1771
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发表时间：
2008-12
影响因子：
1.8
通讯作者：
T. Prasanth;S. Mittal
中科院分区：
文献类型：
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作者：
T. Prasanth;S. Mittal
详细研究了阻塞对低非维质量（m*=10）圆柱在层流状态下涡激振动的影响。利用稳定时空有限元公式，求解了二维原始变量形式的不可压缩流动方程。当堵塞率为5%时，圆柱体的横向响应在同步/锁定区域的两端是滞后的。然而，对于1%的阻塞，滞后只发生在同步/锁定区域的较高Re端。在其他阻塞处进行了计算，以了解其对滞回行为的影响。同步下端磁滞回线随着堵塞的减小而减小，堵塞小于等于2.5%时完全消除。另一方面，在同步/锁定的较高Re端，所有阻塞值都存在滞后。虽然发现所有堵塞的峰值横向振荡幅度是相同的（~ 0.6D），但气动系数的峰值随着堵塞而显著变化。均方根值随堵塞变化较小。研究了计算域的流向范围对滞回特性的影响。升力和横向位移之间的相位在同步区域的大约中间显示出近180°的跳跃。这种跳跃不是滞后的，与堵塞无关。版权所有©2008 John Wiley & Sons， Ltd
The effect of the blockage on vortex‐induced vibrations of a circular cylinder of low non‐dimensional mass (m*=10) in the laminar flow regime is investigated in detail. A stabilized space–time finite element formulation is utilized to solve the incompressible flow equations in primitive variables form in two dimensions. The transverse response of the cylinder is found to be hysteretic at both ends of synchronization/lock‐in region for 5% blockage. However, for the 1% blockage hysteresis occurs only at the higher Re end of synchronization/lock‐in region. Computations are carried out at other blockages to understand its effect on the hysteretic behavior. The hysteresis loop at the lower Re end of the synchronization decreases with decrease in blockage and is completely eliminated for blockage of 2.5% and less. On the other hand, hysteresis persists for all values of blockage at the higher Re end of synchronization/lock‐in. Although the peak transverse oscillation amplitude is found to be same for all blockage (∼0.6D), the peak value of the aerodynamic coefficients vary significantly with blockage. The r.m.s. values show lesser variation with blockage. The effect of streamwise extent of computational domain on hysteretic behavior is also studied. The phase between the lift force and transverse displacement shows a jump of almost 180° at, approximately, the middle of the synchronization region. This jump is not hysteretic and is independent of blockage. Copyright © 2008 John Wiley & Sons, Ltd.