Vortex-magnetic competition and regime transitions in antiparallel flux tubes

Abstract

Vortex–magnetic interactions shape magnetohydrodynamic (MHD) turbulence, influencing energy transfer in astrophysical, geophysical and industrial systems. In the solar atmosphere, granular-scale vortex flows couple strongly with magnetic fields, channelling energy into the corona. At high Reynolds numbers, vorticity and magnetic fields are nearly frozen into the charged fluid, and MHD flows emerge from the Lorentz force mediated interactions between coherent vortex structures in matter 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 Ni , 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 Ni , classical vortex dynamics dominates, driving joint vortex–magnetic reconnection, and amplifying magnetic energy via a dynamo effect. At moderate Ni , the system oscillates between vorticity-driven attraction and magnetic damping, triggering instabilities and nonlinear interactions that spawn secondary filaments and drive an energy cascade. At high Ni , Lorentz forces suppress vortex interactions, aligning the tubes axially while disrupting vortex cores and rapidly converting magnetic to kinetic energy. These findings reveal how the inertial–Lorentz balance governs energy transfer and coherent structure formation in MHD turbulence, offering insight into vortex–magnetic co-evolution in astrophysical plasmas.