Interactions between vortex tubes and magnetic-flux rings at high kinetic and magnetic Reynolds numbers

Kivotides, Demosthenes (2018) Interactions between vortex tubes and magnetic-flux rings at high kinetic and magnetic Reynolds numbers. Physical Review Fluids, 3 (3). 033701. ISSN 2469-990X (https://doi.org/10.1103/PhysRevFluids.3.033701)

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Abstract

The interactions between vortex tubes and magnetic-flux rings in incompressible MHD are investigated at high kinetic and magnetic Reynolds numbers, and over a wide range of the interaction parameter. The latter is a measure of the turnover time of the large-scale fluid motions in units of the magnetic damping time, or of the strength of the Lorentz force in units of the inertial force. The small interaction parameter results, that are related to kinematic turbulent dynamo studies, indicate the evolution of magnetic-rings into flattened spirals wrapped around the vortex tubes. This process is also observed at intermediate interaction parameter values, only now the Lorentz force creates new vortical structures at the magnetic spiral edges, that have a striking solenoid vortex-line structure, and endow the flattened magnetic-spiral surfaces with a curvature. At high interaction parameter values, the decisive physical factor is Lorentz force effects. The latter create two (adjacent to the magnetic-ring) vortex rings, that reconnect with the vortex tube by forming an intriguing, serpentine-like, vortex-line structure, and generate, in turn, two new magnetic rings, adjacent to the initial one. In this regime, the morphologies of the vorticity and magnetic field structures are similar. The effects of these structures on kinetic and magnetic energy spectra, as well as on the direction of energy transfer between flow and magnetic fields are also indicated.

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