Numerical study of magnetic island coalescence using magnetohydrodynamics with adaptively embedded particle-in-cell model
Numerical study of magnetic island coalescence using magnetohydrodynamics with adaptively embedded particle-in-cell model
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DOI：
10.1063/5.0122087
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发表时间：
2022-12
期刊：
影响因子：
1.6
通讯作者：
Dion Li;Yuxi Chen;C. Dong;Liang Wang;G. Tóth
中科院分区：
文献类型：
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作者：
Dion Li;Yuxi Chen;C. Dong;Liang Wang;G. Tóth
无碰撞磁重联通常需要动力学处理，这通常与基于流体的模型相比在计算上昂贵。在这项研究中，我们使用磁流体力学与自适应嵌入粒子在细胞（MHD-AEPIC）模型来研究两个磁通绳的相互作用。这种创新的模型嵌入一个或多个自适应PIC区域到一个全球MHD模拟域，这样的动力学处理只适用于区域的动力学物理是突出的。我们比较了三种情况下的模拟结果：（1）自适应嵌入PIC区域的MHD，（2）静态（或固定）嵌入PIC区域的MHD，和（3）完整的PIC模拟。在分析它们的重联率和磁岛分离以及离子压力张量元和离子无旋性时，比较产生了很好的一致性。为了在这三种情况下达到很好的一致性，需要在MHD域内建立大的自适应PIC区域，这表明磁岛合并问题本质上是高度动力学的，其中宏观尺度MHD和微观尺度动力学物理之间的耦合是重要的。
Collisionless magnetic reconnection typically requires kinetic treatment that is, in general, computationally expensive compared to fluid-based models. In this study, we use the magnetohydrodynamics with an adaptively embedded particle-in-cell (MHD-AEPIC) model to study the interaction of two magnetic flux ropes. This innovative model embeds one or more adaptive PIC regions into a global MHD simulation domain such that the kinetic treatment is only applied in regions where the kinetic physics is prominent. We compare the simulation results among three cases: (1) MHD with adaptively embedded PIC regions, (2) MHD with statically (or fixed) embedded PIC regions, and (3) a full PIC simulation. The comparison yields good agreement when analyzing their reconnection rates and magnetic island separations as well as the ion pressure tensor elements and ion agyrotropy. In order to reach good agreement among the three cases, large adaptive PIC regions are needed within the MHD domain, which indicates that the magnetic island coalescence problem is highly kinetic in nature, where the coupling between the macro-scale MHD and micro-scale kinetic physics is important.