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Renormalization Group Analysis of the Turbulent Hydromagnetic Dynamo: The Effect of Nonstationarity
The Astrophysical Journal Supplement Series ( IF 8.6 ) Pub Date : 2020-11-23 , DOI: 10.3847/1538-4365/abb8dc
Krzysztof A. Mizerski

The turbulent hydromagnetic dynamo is a process of magnetic field generation by chaotic flow of an electrically conducting fluid (plasma, liquid iron, etc.). It is responsible for generation of large-scale magnetic fields of astrophysical objects such as planets, stars, accretion disks, galaxies, galaxy clusters, etc. In particular, the dynamical process of induction of large-scale fields by highly conducting plasma has been very difficult to understand, as very low resistivity is not capable of creating a phase shift between magnetic and kinetic components of waves, making their interaction ineffective for generation of a large-scale electromotive force (EMF). The aim of the analysis presented here is to demonstrate that when the typically invoked statistical stationarity of turbulence is relaxed, large-scale magnetic fields can be very effectively generated by low-resistivity plasma. The renormalization group technique is applied to extract the final expression for the mean EMF from the fully nonlinear dynamical equations (Navier–Stokes, induction equation), and the mean field equations are solved for a force-free mode. Nonstationarity is shown to strongly enhance the process of large-scale EMF generation via wave interactions, and the dynamo effect induced by nonstationarity is proved to be effective. The results are also used to demonstrate the influence of magnetic fields and nonstationarity on energy and helicity spectra of turbulent flows.



中文翻译:

湍流水磁发电机的重归一化组分析:非平稳性的影响

湍流的水磁发电机是通过导电流体(等离子,铁水等)的混沌流动而产生磁场的过程。它负责产生天文学物体(例如行星,恒星,吸积盘,星系,星系团等)的大范围磁场。特别是,通过高传导等离子体感应大范围场的动力学过程非常很难理解,因为极低的电阻率无法在电磁波和动力学波之间产生相移,从而使它们的相互作用对于生成大规模电动势(EMF)无效。此处进行分析的目的是证明,当通常调用的湍流统计平稳性放松时,低电阻率等离子体可以非常有效地产生大范围的磁场。应用重归一化组技术从完全非线性的动力学方程(Navier–Stokes,归纳方程)中提取平均EMF的最终表达式,并针对无力模式求解平均场方程。非平稳性通过波相互作用强烈增强了大规模EMF生成过程,并且非平稳性引起的发电机效应被证明是有效的。结果还用于证明磁场和非平稳性对湍流能量和螺旋光谱的影响。感应方程式),并针对无力模式求解平均场方程式。非平稳性通过波相互作用强烈增强了大规模EMF生成过程,并且非平稳性引起的发电机效应被证明是有效的。结果还用于证明磁场和非平稳性对湍流能量和螺旋光谱的影响。感应方程式),并针对无力模式求解平均场方程式。非平稳性通过波相互作用强烈增强了大规模EMF生成过程,并且非平稳性引起的发电机效应被证明是有效的。结果还用于证明磁场和非平稳性对湍流能量和螺旋光谱的影响。

更新日期:2020-11-23
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