Simulations of magneto-convection in the solar photosphere Equations, methods, and results of the MURaM code
Simulations of magneto-convection in the solar photosphere Equations, methods, and results of the MURaM code
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DOI：
10.1051/0004-6361:20041507
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发表时间：
2005
影响因子：
6.5
通讯作者：
A. Vögler;S. Shelyag;M. Schüssler;F. Cattaneo;T. Emonet;T. Linde
中科院分区：
文献类型：
--
作者：
A. Vögler;S. Shelyag;M. Schüssler;F. Cattaneo;T. Emonet;T. Linde
我们已经开发了一个三维磁流体动力学模拟程序的应用在太阳对流区和光球。该代码包括一个非本地和非灰色辐射传输模块，并考虑到部分电离的影响。它的并行设计是基于区域分解，这使得它适用于分布式存储器结构的并行计算机上。我们给出的方程和数值方法的描述，并提出了太阳谱区的模拟结果。从200 G的均匀垂直场开始，通量驱逐和对流场放大的过程导致强的，主要是垂直场嵌入在颗粒的下行流网络和弱的，随机取向的字段填充热颗粒的上行流的二分法。强场形成具有薄的片状结构的磁网络，该结构沿着向下流动通道延伸，并且微孔直径高达1000 km，其偶尔形成在几个向下流动通道合并的顶点处.在可见光表面周围的光学深度统一，强场浓度的压力平衡与弱磁化的环境，并达到场强高达2千克，大大超过了相应的值均分的动能密度的对流运动。由于辐射的引导，小通量浓度突出为明亮的特征，而较大的微孔由于对流能量传输的抑制而在亮度图中显得较暗。磁网络的整体形状在比对流周转时间大得多的时间尺度上缓慢变化，而磁通量在网络内不断重新分布，导致磁通量浓度的连续形成和溶解。
We have developed a 3D magnetohydrodynamics simulation code for applications in the solar convection zone and photosphere. The code includes a non-local and non-grey radiative transfer module and takes into account the effects of partial ionization. Its parallel design is based on domain decomposition, which makes it suited for use on parallel computers with distributed memory architecture. We give a description of the equations and numerical methods and present the results of the simulation of a solar plage region. Starting with a uniform vertical field of 200 G, the processes of flux expulsion and convective field amplification lead to a dichotomy of strong, mainly vertical fields embedded in the granular downflow network and weak, randomly oriented fields filling the hot granular upflows. The strong fields form a magnetic network with thin, sheet- like structures extending along downflow lanes and micropores with diameters of up to 1000 km which form occasionally at vertices where several downflow lanes merge. At the visible surface around optical depth unity, the strong field concentrations are in pressure balance with their weakly magnetized surroundings and reach field strengths of up to 2 kG, strongly exceeding the values corresponding to equipartition with the kinetic energy density of the convective motions. As a result of the channelling of radiation, small flux concentrations stand out as bright features, while the larger micropores appear dark in brightness maps owing to the suppression of the convective energy transport. The overall shape of the magnetic network changes slowly on a timescale much larger than the convective turnover time, while the magnetic flux is constantly redistributed within the network leading to continuous formation and dissolution of flux concentrations.