On vortex rings around vortices: an optimal mechanism
On vortex rings around vortices: an optimal mechanism
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关于涡流周围的涡环：最优机制
DOI：
10.1017/s0022112007005198
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发表时间：
2007
影响因子：
3.7
通讯作者：
P. Brancher
中科院分区：
文献类型：
--
作者：
A. Antkowiak;P. Brancher
受到流体动力学噪声（例如湍流）影响的稳定柱状涡呈现出反复出现的行为，例如涡核外围涡环的系统性发展。这种现象缺乏全面的解释，部分原因是它与严格意义上的不稳定性无关。本论文的目的是确定的物理机制触发这一内在特征的涡使用最佳扰动分析作为一种工具的调查。我们发现，涡环的产生与特定扰动的强烈和快速放大有关，这些扰动以方位角速度条纹的形式最终演变成由局部科里奥利力的旋转部分产生的方位角涡卷。因此，这种演变似乎遵循了与经典提升观点相反的情况，即滚动会产生条纹。
Stable columnar vortices subject to hydrodynamic noise (e.g. turbulence) present recurrent behaviours, such as the systematic development of vortex rings at the periphery of the vortex core. This phenomenon lacks a comprehensive explanation, partly because it is not associated with an instability stricto sensu. The aim of the present paper is to identify the physical mechanism triggering this intrinsic feature of vortices using an optimal perturbation analysis as a tool of investigation. We find that the generation of vortex rings is linked to the intense and rapid amplification of specific disturbances in the form of azimuthal velocity streaks that eventually evolve into azimuthal vorticity rolls generated by the rotational part of the local Coriolis force. This evolution thus appears to follow a scenario opposite to the classical lift-up view, where rolls give rise to streaks.