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arXiv 2408.08960physics.comp-phastro-ph.HEphysics.plasm-ph
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网格细化在相对论磁重联中的应用

Application of mesh refinement to relativistic magnetic reconnection

Revathi Jambunathan, Henry Jones, Lizzette Corrales, Hannah Klion, Michael Rowan, Andrew Myers, Weiqun Zhang, Jean-Luc Vay

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AI总结：

本研究针对相对论磁重联模拟的尺度差异问题，提出结合PSATD求解器、界面吸收层的网格细化方法，在二维模拟中以更少计算资源实现了与高分辨率基准一致的结果，为高效三维重联研究奠定基础。

摘要：

在相对论磁重联过程中，反向平行的磁场会发生拓扑结构的快速变化，以非热粒子加速的形式释放大量能量。本研究探索了将网格细化应用于二维重联模拟的方法，以高效模拟固有的空间尺度差异问题。我们系统研究了网格细化的影响，并确定了为缓解粗细网格界面处的非物理伪影所需对算法做出的必要修改。我们采用了超高阶伪谱解析时域（Pseudo-Spectral Analytical Time-Domain, PSATD）麦克斯韦求解器，分析其使用如何缓解有限差分时域（finite-difference time-domain, FDTD，又称“Yee”）方法中出现的数值色散问题。我们在粗细网格界面处引入了吸收层，以消除网格细化过程中产生的虚假效应。我们还研究了在吸收层中对电磁场和电流密度进行阻尼处理，如何有助于防止粗细网格界面处出现非物理的电荷与电流密度累积。在二维磁重联模拟中采用8倍的网格细化比例时，我们获得了与高分辨率基准模拟高度一致的结果，而仅使用了基准模拟所需36%的宏粒子和71%的节点小时数。本文提出的方法尤其适用于三维系统，预计其在三维系统中可比二维场景节省更多内存，为未来开展全面、计算高效的三维重联研究提供了可能。

英文摘要：

During relativistic magnetic reconnection, antiparallel magnetic fields undergo a rapid change in topology, releasing a large amount of energy in the form of non-thermal particle acceleration. This work explores the application of mesh refinement to 2D reconnection simulations to efficiently model the ineherent disparity in length-scales. We have systematically investigated the effects of mesh refinement and determined necessary modifications to the algorithm required to mitigate non-physical artifacts at the coarse-fine interface. We have used the ultrahigh-order Pseudo-Spectral Analytical Time-Domain (PSATD) Maxwell solver to analyze how its use can mitigate the numerical dispersion that occurs with the finite-difference time-domain (FDTD) (or ``Yee'') method. Absorbing layers are introduced at the coarse-fine interface to eliminate spurious effects that occur with mesh refinement. We also study how damping the electromagnetic fields and current density in the absorbing layer can help prevent the non-physical accumulation of charge and current density at the coarse-fine interface. Using a mesh refinement ratio of 8 for two-dimensional magnetic reconnection simulations, we obtained good agreement with the high resolution baseline simulation, using only 36% of the macroparticles and 71% of the node-hours needed for the baseline. The methods presented here are especially applicable to 3D systems where higher memory savings are expected than in 2D, enabling comprehensive, computationally efficient 3D reconnection studies in the future.

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