Vortex rings impinging on walls: axisymmetric and three-dimensional simulations
Vortex rings impinging on walls: axisymmetric and three-dimensional simulations
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DOI：
10.1017/s0022112093002903
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发表时间：
1993-11
影响因子：
3.7
通讯作者：
P. Orlandi;R. Verzicco
中科院分区：
文献类型：
--
作者：
P. Orlandi;R. Verzicco
精确的数值模拟的涡环撞击在平坦的边界上显示出相同的功能在实验中观察到的。与自由滑动壁的影响的结果比较非常好，与以前的数值模拟，使用谱方法，也在定性与实验一致。目前的模拟主要致力于研究环与无滑移壁相互作用的更真实的情况，这是步行者等人（1987）实验研究的结果。所有研究的雷诺数都显示出实验和模拟之间非常好的一致性，并且在Rev > 1000时，可以看到从壁面喷射出一个新的环。轴对称模拟表明，涡配对是产生新环喷射的物理机制。还进行了三维模拟，以研究方位不稳定性的影响。这些模拟已经证实，高波数不稳定性起源于压缩阶段的次级环内的主要一个。通过对应变率张量和涡度排列的分析，解释了次级环的大的不稳定性。本文还讨论了被动标量与涡度场的区别。
Accurate numerical simulations of vortex rings impinging on flat boundaries revealed the same features observed in experiments. The results for the impact with a free-slip wall compared very well with previous numerical simulations that used spectral methods, and were also in qualitative agreement with experiments. The present simulation is mainly devoted to studying the more realistic case of rings interacting with a no-slip wall, experimentally studied by Walker et al. (1987). All the Reynolds numbers studied showed a very good agreement between experiments and simulations, and, at Rev > 1000 the ejection of a new ring from the wall was seen. Axisymmetric simulations demonstrated that vortex pairing is the physical mechanism producing the ejection of the new ring. Three-dimensional simulations were also performed to investigate the effects of azimuthal instabilities. These simulations have confirmed that high-wavenumber instabilities originate in the compression phase of the secondary ring within the primary one. The large instability of the secondary ring has been explained by analysis of the rate-of-strain tensor and vorticity alignment. The differences between passive scalars and the vorticity field have been also investigated.