RAPID RELAXATION OF AN AXISYMMETRIC VORTEX
RAPID RELAXATION OF AN AXISYMMETRIC VORTEX
复制标题
轴对称涡旋的快速弛豫
DOI：
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
J. Lingevitch
中科院分区：
文献类型：
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作者：
A. Bernoff;J. Lingevitch
本文讨论了二维轴对称大雷诺数（Re）单极子在受摄动后会在比黏性演化时间尺度（Re）快得多的时间尺度（Re1/3）上恢复到轴对称状态。证明了任意扰动可以被分解成三个部分；首先，轴对称片对应于轻微的径向涡度再分布；第二，对应于原涡旋中心的一个小位移的平移块；最后，由于Rhines和Young研究的剪切/扩散平均机制，在Re1/3时间尺度上衰减的非轴对称微扰[J]。流体力学，133,133(1983)]对于被动标量和Lundgren[物理学]。[j] .流体力学学报，2009,27(6):1104 - 1104。用兰姆单极子的典型例子验证了这一机理。这一结果为大雷诺数流中单极结构的持久性提供了物理解释，例如衰减湍流。
In this paper it is argued that a two‐dimensional axisymmetric large Reynolds number (Re) monopole when perturbed will return to an axisymmetric state on a time scale (Re1/3) that is much faster than the viscous evolution time scale (Re). It is shown that an arbitrary perturbation can be broken into three pieces; first, an axisymmetric piece corresponding to a slight radial redistribution of vorticity; second, a translational piece which corresponds to a small displacement of the center of the original vortex; and finally, a nonaxisymmetric perturbation which decays on the Re1/3 time scale due to a shear/diffusion averaging mechanism studied by Rhines and Young [J. Fluid Mech. 133, 133 (1983)] for a passive scalar and Lundgren [Phys. Fluids 25, 2193 (1982)] for vorticity. This mechanism is verified numerically for the canonical example of a Lamb monopole. This result suggests a physical explanation for the persistence of monopole structures in large Reynolds flows, such as decaying turbulence.