Investigating Turbulence Effects on Magnetic Reconnection Rates through 3D Resistive Magnetohydrodynamic Simulations
通过三维电阻磁流体动力学模拟研究湍流对磁重联率的影响
We investigate the impact of turbulence on magnetic reconnection through high-resolution 3D magnetohydrodynamic (MHD) simulations, spanning Lundquist numbers from S = 10<SUP>3</SUP> to 10<SUP>6</SUP>. Building on the A. Lazarian & E. T. Vishniac theory, which asserts reconnection rate independence from ohmic resistivity, we introduce small-scale perturbations until t = 0.1 t<SUB>A</SUB>. Even after the perturbations cease, turbulence persists, resulting in sustained high reconnection rates of V<SUB>rec</SUB>/V<SUB>A</SUB> ∼ 0.03─0.08. These rates exceed those generated by resistive tearing modes (plasmoid chain) in 2D and 3D MHD simulations by factors of 5─6. Our findings match observations in solar phenomena and previous 3D MHD global simulations of solar flares, accretion flows, and relativistic jets. The simulations show a steady-state fast reconnection rate compatible with the full development of turbulence in the system, demonstrating the robustness of the process in turbulent environments. We confirm reconnection rate independence from the Lundquist number, supporting Lazarian and Vishniac's theory of fast turbulent reconnection. Additionally, we find a mild dependence of V<SUB>rec</SUB> on the plasma─β parameter, decreasing from 0.036 to 0.028 (in Alfvén units) as β increases from 2.0 to 64.0 for simulations with a Lundquist number of 10<SUP>5</SUP>. Lastly, we explore the magnetic Prandtl number's (Pr<SUB>m</SUB> = ν/η) influence on the reconnection rate and find it negligible during the turbulent regime across the range tested, from Pr<SUB>m</SUB> = 1 to 60.
展开 ▾亮点:作者只注入短时小尺度多模扰动而非连续驱动,便获得自持湍流和快速重联,速率比纯撕裂模/等离子体链高约5–6倍;并首次在S=10^5下系统检验了β和Prm的影响。
经典Sweet–Parker重联速率随Lundquist数增大而急剧下降,难以解释天体物理中的快速能量释放;Lazarian & Vishniac 1999 提出三维湍流可使重联率与电阻率解耦,成为关键理论转折。此后,Kowal+ 2009 等通过连续驱动湍流的3D MHD模拟初步验证了这一图像,而 Huang & Bhattacharjee 2016 与 Beg+ 2022 在高Lundquist数下进一步看到自生湍流阶段,但其重联率仍受撕裂模主导或仅略高于撕裂模。本文以短时小尺度多模扰动替代连续驱动,展示湍流可自持并给出V_rec/V_A≈0.03–0.08,比纯撕裂模链高约5–6倍,同时扩展了 Kowal+ 2017 关于弱β依赖的结果,并发现Prm=1–60范围内影响可忽略。这些结果强化了湍流重联对太阳耀斑、吸积流和相对论喷流等环境的适用性;未来研究可进一步改变湍流注入尺度并检验其对粒子加速与耗散统计的影响。
预印本 2024-05-24 · 接收 2025-04-28 · 刊出 2025-07-09 · 收录 2026-08-20