AN EXPLICIT SCHEME FOR INCORPORATING AMBIPOLAR DIFFUSION IN A MAGNETOHYDRODYNAMICS CODE
AN EXPLICIT SCHEME FOR INCORPORATING AMBIPOLAR DIFFUSION IN A MAGNETOHYDRODYNAMICS CODE
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将双极扩散纳入磁流体动力学代码的显式方案
DOI：
10.1088/0067-0049/181/2/413
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
P. Wiita
中科院分区：
文献类型：
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作者：
Eunwoo Choi;Jongsoo Kim;P. Wiita
我们描述了一种将强耦合近似中的双极扩散合并到基于总变差递减方案的多维磁流体动力学（MHD）代码中的方法。双极扩散项的贡献由显式有限差分算子以完全不分裂的方式包含，保持二阶精度。磁通量插值约束输运方案始终准确地确保磁场的无发散条件。超级时间步进方法用于加速高分辨率计算和/或强双极扩散中的时间步长。我们执行了两个测试问题，即稳态斜 C 型激波和阿尔芬波的衰减，证实了我们数值方法的准确性和鲁棒性。双极扩散可压缩 MHD 湍流的模拟结果表明，我们的方法具有灵活性，并且能够在双极扩散的情况下跟踪复杂的 MHD 流。这些模拟表明，MHD 湍流的耗散率受到双极扩散强度的强烈影响。
We describe a method for incorporating ambipolar diffusion in the strong coupling approximation into a multidimensional magnetohydrodynamic (MHD) code based on the total variation diminishing scheme. Contributions from ambipolar diffusion terms are included by explicit finite-difference operators in a fully unsplit way, maintaining second-order accuracy. The divergence-free condition of magnetic fields is exactly ensured at all times by a flux-interpolated constrained transport scheme. The super time-stepping method is used to accelerate the time step in high-resolution calculations and/or in strong ambipolar diffusion. We perform two test problems, the steady-state oblique C-type shocks and the decay of Alfvén waves, confirming the accuracy and robustness of our numerical approach. Results from the simulations of the compressible MHD turbulence with ambipolar diffusion show the flexibility of our method as well as its ability to follow complex MHD flows in the presence of ambipolar diffusion. These simulations show that the dissipation rate of the MHD turbulence is strongly affected by the strength of ambipolar diffusion.