论文标题
太阳大气中的涡流演变：旋转强度的动力方程
Vortices evolution in the solar atmosphere: A dynamical equation for the swirling strength
论文作者
论文摘要
我们通过采用和得出两个涡流识别标准的分析演化方程来研究太阳大气中的涡流动力学。所使用的两个标准是涡度和旋转强度。在剪切流的存在下，涡度可能会偏向，但其动力学方程是众所周知的。旋转强度是鉴定涡流流的更精确的标准，但其演化方程尚不清楚。因此，我们探索了旋转强度的动态方程的可能性。然后，我们应用两个方程式来分析用CO5bold代码产生的太阳大气的辐射MHD模拟。我们详细介绍了旋转强度标准和其进化方程的数学推导。该方程式以前不存在，它构成了一种新型工具，适合分析（磁 - ）流体动力学中的各种问题。通过将该方程应用于数值模型，我们发现流体动力学和磁性斜压力是导致对流区和光球中涡流产生的驱动物理过程。在染色层中较高，仅磁性术语占主导地位。此外，我们发现旋转强度是以混乱的方式以小尺度产生的，尤其是在磁通量浓度内。旋转强度代表了鉴定湍流中涡流（例如太阳大气中的涡流）的适当标准。此外，其演化方程是在本文中得出的，它是获取有关这些涡流动力学的精确信息以及负责其生产和进化的物理机制的关键信息。由于该方程式可用，因此旋转强度现在是研究（磁 - ）流体动力学涡流动力学的理想数量。
We study vortex dynamics in the solar atmosphere by employing and deriving the analytical evolution equations of two vortex identification criteria. The two criteria used are vorticity and the swirling strength. Vorticity can be biased in the presence of shear flows, but its dynamical equation is well known; the swirling strength is a more precise criterion for the identification of vortical flows, but its evolution equation is not known yet. Therefore, we explore the possibility of deriving a dynamical equation for the swirling strength. We then apply the two equations to analyze radiative MHD simulations of the solar atmosphere produced with the CO5BOLD code. We present a detailed review of the swirling strength criterion and the mathematical derivation of its evolution equation. This equation did not exist in the literature before and it constitutes a novel tool that is suitable for the analysis of a wide range of problems in (magneto-)hydrodynamics. By applying this equation to numerical models, we find that hydrodynamical and magnetic baroclinicities are the driving physical processes responsible for vortex generation in the convection zone and the photosphere. Higher up in the chromosphere, the magnetic terms alone dominate. Moreover, we find that the swirling strength is produced at small scales in a chaotic fashion, especially inside magnetic flux concentrations. The swirling strength represents an appropriate criterion for the identification of vortices in turbulent flows, such as those in the solar atmosphere. Moreover, its evolution equation, which is derived in this paper, is pivotal for obtaining precise information about the dynamics of these vortices and the physical mechanisms responsible for their production and evolution. Since this equation is available, the swirling strength is now the ideal quantity to study the dynamics of vortices in (magneto-)hydrodynamics.
