Study on vorticity structures in late flow transition
Study on vorticity structures in late flow transition
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DOI：
10.1063/1.5045795
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发表时间：
2018-05
影响因子：
4.6
通讯作者：
Xiangrui Dong;G. Dong;Chaoqun Liu
中科院分区：
文献类型：
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作者：
Xiangrui Dong;G. Dong;Chaoqun Liu
涡度和涡旋是两个不同但相关的概念。本文着重研究了涡量的产生和发展以及涡内外涡量结构。涡是涡量超过形变的区域。涡不能直接用涡量来表示。在流动转捩过程中，除了来自于侧边界并终止于侧边界的涡线外，在区域内还大量产生了另一种涡线，即自闭合涡线，即涡环。这些新的涡环出现在发夹涡的头部和腿部。根据涡量输运方程，涡量环的产生和增长是由涡量的建立引起的。另一方面，涡旋的形成是涡度线拉伸、倾斜和扭曲的结果。在流动转变过程中既产生新的涡量又产生新的涡。根据Helmholtz涡量通量守恒定律，涡量线在流场中不能中断、开始或终止，新产生的涡量只有一种形式，即涡量环。此外，一个有趣的发现是，一个单一的发夹涡是由几种类型的涡线，可能来自侧边界，整个涡环和部分涡环。
Vorticity and vortex are two different but related concepts. This paper focuses on the investigation of vorticity generation and development, and vorticity structure inside/ outside the vortex. Vortex is a region where the vorticity overtakes deformation. Vortex cannot be directly represented by the vorticity. Except for those vorticity lines which come from and end at side boundaries, another type of vorticity, self-closed vorticity lines named vorticity rings, is numerously generated inside the domain during flow transition. These new vorticity rings are found around the hairpin vortex heads and legs. The generation and growth of vorticity rings are produced by the buildup of the vortices according to the vorticity transport equation. On the other hand, vortex buildup is a consequence of vorticity line stretching, tilting and twisting. Both new vorticity and new vortices are generated during the flow transition. According to the Helmholtz vorticity flux conservation law, vorticity line cannot be interrupted, started, or ended inside the flow field, the newly produced vorticity has only one form which is the vorticity rings. In addition, an interesting finding is that a single hairpin vortex consists of several types of vorticity lines which could come from the side boundaries, whole vorticity rings and part of vorticity rings.