Evolution of a single wake behind a pair of bluff bodies
Evolution of a single wake behind a pair of bluff bodies
复制标题
DOI：
10.1017/s002211208500307x
复制
发表时间：
1985-10
影响因子：
3.7
通讯作者：
C. Williamson
中科院分区：
文献类型：
--
作者：
C. Williamson
本文用多种流动显示方法研究了一对并排放置的海崖体后的流动。在物体之间的临界间隙尺寸以上，涡旋脱落同步发生，无论是同相还是反相。先前已经假设，这种同步形成包括两个平行的分别同相和反相的涡街的尾流。在本论文中，我们发现，两个反相街道确实形成，虽然同相脱落导致一个单一的大规模的发展。在圆柱体上同时形成的涡流在下游彼此围绕旋转，每对涡流形成一个“二元涡流”。组合尾流包括一条这样的涡列，我们称之为二元涡列。在海崖体之间的临界间隙尺寸以下，流动变得不对称。我们观察到，在这个制度的某些谐波模式的旋涡脱落，其中脱落频率在一侧的尾流是一个倍数的其他。再次，下游形成大规模尾流。目前的观察导致一个新的解释热线频率数据从其他研究的谐波模式。
In this paper the flow behind a pair of bluff bodies placed side by side in a stream is studied using a variety of flow-visualization methods. Above a critical gap size between the bodies, vortex-shedding synchronization occurs, either in phase or in antiphase. It has previously been assumed that such synchronization forms a wake comprising two parallel vortex streets in phase and in antiphase respectively. In the present paper we find that two antiphase streets are indeed formed, although in-phase shedding leads to the development of a single large-scale wake. The vortices which are formed simultaneously at the cylinders rotate around one another downstream, each pair forming a ‘binary vortex’. The combined wake comprises a street of such vortices, which we term a binary vortex street. Below a critical gap size between the bluff bodies the flow becomes asymmetric. We observe in this regime certain harmonic modes of vortex shedding whereby the shedding frequency on one side of the wake is a multiple of that on the other. Again, a large-scale wake is formed downstream. The present observations lead to a new interpretation of hot-wire-frequency data from other studies in terms of the harmonic modes.