The work extends the computational model EULAG-MHD to include Hall magnetohydrodynamics (HMHD)---important to explore physical systems undergoing fast magnetic reconnection at the order of the ion inertial length scale. Examples include solar transients along with reconnections in magnetosphere, magnetotail and laboratory plasmas. The paper documents the results of two distinct sets of implicit large-eddy simulations in the presence and absence of the Hall forcing term, initiated with an unidirectional sinusoidal magnetic field. The HMHD simulation while benchmarking the code also emphasizes the complexity of three dimensional (3D) evolution over its two dimensional (2D) counterpart. The magnetic reconnections onset significantly earlier in HMHD. Importantly, the magnetic field generated by the Hall term breaks any inherent symmetry, ultimately making the evolution 3D. The resulting 3D reconnections develop magnetic flux ropes and magnetic flux tubes. Projected on the reconnection plane, the ropes and tubes appear as magnetic islands, which later break into secondary islands, and finally coalesce to generate an X-type neutral point. These findings are in agreement with the theory and contemporary simulations of HMHD, and thus verify our extension of the EULAG-MHD model. The second set explores the influence of the Hall forcing on generation and ascend of a magnetic flux rope from sheared magnetic arcades---a novel scenario instructive in understanding the coronal transients. The rope evolves through intermediate complex structures, ultimately breaking locally because of reconnections. Interestingly, the breakage occurs earlier in the presence of the Hall term, signifying faster dynamics leading to magnetic topology favorable for reconnections.

中文翻译：

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霍尔磁流体动力学中三维相干结构的演化

这项工作扩展了计算模型 EULAG-MHD 以包括霍尔磁流体动力学 (HMHD)——这对于探索在离子惯性长度尺度量级进行快速磁重联的物理系统很重要。例子包括太阳瞬变以及磁层、磁尾和实验室等离子体中的重新连接。该论文记录了在存在和不存在霍尔强迫项的情况下，由单向正弦磁场启动的两组不同的隐式大涡模拟的结果。HMHD 模拟在对代码进行基准测试时还强调了三维 (3D) 演化相对于其二维 (2D) 对应物的复杂性。磁重联在 HMHD 中显着更早开始。重要的是，霍尔项产生的磁场打破了任何固有的对称性，最终使进化 3D。由此产生的 3D 重新连接形成了磁通量绳和磁通量管。投影到重连平面上，绳索和管子表现为磁岛，然后分裂成次级岛，最后合并形成X型中性点。这些发现与 HMHD 的理论和当代模拟一致，从而验证了我们对 EULAG-MHD 模型的扩展。第二组探讨了霍尔强迫对来自剪切磁拱的磁通量绳的产生和上升的影响——一种有助于理解日冕瞬变的新场景。绳索通过中间复杂的结构演变，最终由于重新连接而局部断裂。有趣的是，在霍尔项存在的情况下，断裂发生得更早，