Multi-scale dynamics of magnetic flux tubes and inverse magnetic energy transfer
Multi-scale dynamics of magnetic flux tubes and inverse magnetic energy transfer
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磁通管的多尺度动力学和逆磁能传递
DOI：
10.1017/s0022377820000641
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发表时间：
2020
影响因子：
2.5
通讯作者：
Uzdensky, Dmitri A.
中科院分区：
文献类型：
--
作者：
Zhou, Muni;Loureiro, Nuno F.;Uzdensky, Dmitri A.
我们报告了在等离子体的简化磁流体动力学描述中对相同磁通量管的三维阵列的动力学的分析和数值研究。我们提出，该系统的长期演化是由通量管合并决定的，并且这种合并受到相关（理想）不变量守恒的动态约束，即。每根管子的磁势和轴向通量。我们还提出，在垂直于合并平面的方向上，通量管以临界平衡的方式演化。这些概念使我们能够构建一个分析模型，用于解释磁能和含能尺度等量如何随着时间的函数而演变。特别重要的是这样的结论：与二维系统一样，该系统表现出仅在系统尺度上终止的磁能逆转移。我们进行直接数值模拟来证实这些预测并揭示系统演化的其他有趣方面。例如，我们发现早期演化的特点是初始磁能急剧衰减，我们将其归因于电流片的普遍形成。我们还表明，当初始条件是随机的小规模磁种子场时，可以观察到定量相似的磁能逆转移。
We report on an analytical and numerical study of the dynamics of a three-dimensional array of identical magnetic flux tubes in the reduced-magnetohydrodynamic description of the plasma. We propose that the long-time evolution of this system is dictated by flux-tube mergers, and that such mergers are dynamically constrained by the conservation of the pertinent (ideal) invariants, viz. the magnetic potential and axial fluxes of each tube. We also propose that in the direction perpendicular to the merging plane, flux tubes evolve in a critically balanced fashion. These notions allow us to construct an analytical model for how quantities such as the magnetic energy and the energy-containing scale evolve as functions of time. Of particular importance is the conclusion that, like its two-dimensional counterpart, this system exhibits an inverse transfer of magnetic energy that terminates only at the system scale. We perform direct numerical simulations that confirm these predictions and reveal other interesting aspects of the evolution of the system. We find, for example, that the early time evolution is characterized by a sharp decay of the initial magnetic energy, which we attribute to the ubiquitous formation of current sheets. We also show that a quantitatively similar inverse transfer of magnetic energy is observed when the initial condition is a random, small-scale magnetic seed field.
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影响因子：
3.7
作者：
A. Pouquet
通讯作者：
A. Pouquet
DOI：
10.1088/1742-6596/1332/1/012005
发表时间：
2019-11
期刊：
Journal of Physics: Conference Series
影响因子：
--
作者：
Q. Hu;Yu Chen;J. A. Roux
通讯作者：
Q. Hu;Yu Chen;J. A. Roux
影响因子：
4.2
作者：
Muni Zhou;Pallavi Bhat;N. Loureiro;D. Uzdensky
通讯作者：
Muni Zhou;Pallavi Bhat;N. Loureiro;D. Uzdensky
相对论性磁控等离子体中的爆炸性 X 点塌缩
影响因子：
2.5
作者：
M. Lyutikov;L. Sironi;S. Komissarov;O. Porth
通讯作者：
O. Porth
影响因子：
4.6
作者：
D. Biskamp
通讯作者：
D. Biskamp