Vortex–magnetic competition and regime transitions in antiparallel flux tubes

Vortex–magnetic interactions shape magnetohydrodynamic (MHD) turbulence, influencing energy transfer in astrophysical, geophysical, and industrial systems. On the Sun, granular-scale vortex flows strongly couple with magnetic fields, channeling energy into the corona. At high Reynolds numbers, vorticity and magnetic fields are nearly frozen into the charged fluid, and MHD flows emerge from Lorentz-force-mediated interactions between coherent vortex structures and the field. To probe this competition in a controlled setting, we revisit the canonical problem of two antiparallel flux tubes. By varying the magnetic flux threading each tube—and thus sweeping the interaction parameter N_i, which gauges Lorentz-to-inertial force balance—we uncover three distinct regimes: vortex-dominated joint reconnection, instability-triggered cascade, and Lorentz-induced vortex disruption. At low N_i, classical vortex dynamics dominate, driving joint reconnection and amplifying magnetic energy via a dynamo effect. At moderate N_i, the system oscillates between vorticity-driven attraction and magnetic damping, spawning instabilities and secondary filaments that drive an energy cascade. At high N_i, Lorentz forces suppress vortex interactions, align the tubes axially, and disrupt vortex cores, rapidly converting magnetic to kinetic energy. These results reveal how inertial–Lorentz balance governs energy transfer and coherent structure formation in MHD turbulence.