Evolution of vorticity regions of Kármán-vortex-street type
Evolution of vorticity regions of Kármán-vortex-street type
复制标题
卡门涡街型涡度区域的演化
DOI：
10.1016/0169-5983(94)00057-7
复制
发表时间：
1995
影响因子：
1.5
通讯作者：
M. Funakoshi
中科院分区：
文献类型：
--
作者：
M. Funakoshi
本文用数值方法和解析方法研究了卡门涡街型均匀或非均匀圆形涡度区（半径为R）（两排涡度区间距为h，同号涡度区间距为d）的演化。用离散涡方法得到了（hat h，hat d）平面上涡量区合并成几乎平行的涡量层的区域和涡量区继续局部化的区域。这里h= h/R，d= d/R。这种局部化行为的定性解释的理论中，每个相邻的涡区被一个点涡取代。此外，如果初始hat d值很小，则由于外部横向流动而使hat h/hat d从一个小值开始增加会导致向几乎平行的涡量层的过渡。实验结果表明，卡门涡街破裂前的h/d大于0.365。
The evolution of uniform or non-uniform circular vorticity regions (of radius R) of Kármán-vortex-street type (with a distance h between the two rows, and a spacing d of the regions of the same sign) is examined numerically and analytically. The domain in the (hat h, hat d) plane for which the vorticity regions merge to nearly parallel vorticity layers and the domain for which they continue to be localized are obtained using the discrete vortex method. Here hat h= h/R and hat d= d/R. Most of this localized behavior is qualitatively explained by the theory in which each neighboring vorticity region is replaced by a point vortex. Moreover, the increase in hat h/hat d from a small value due to an external transverse flow causes the transition to the nearly parallel vorticity layers if initial hat d value is small. It is suggested that h/d just before the breakdown of the Kármán vortex street in experiments is larger than 0.365.