Simulation of magnetohydrodynamic flows of liquid metals with heat transfer or magnetic stirring

TL;DR

This paper investigates how nonhomogeneous magnetic fields influence liquid metal flows, demonstrating effects on heat transport and vortex dynamics through numerical simulations of magnetic field configurations and oscillations.

Contribution

It introduces a numerical study of magnetic field effects on liquid metal flows, including heat transfer reduction and vortex shedding resonance due to oscillating magnetic obstacles.

Findings

Heat transport decreases with fringe-width in magnetic fields.

Oscillating magnetic obstacles induce vortex shedding similar to solid obstacles.

Drag force and energy transfer depend non-monotonically on oscillation frequency.

Abstract

We discuss the effects of nonhomogeneous magnetic fields in liquid metal flows in two different configurations. In the first configuration, we briefly report the impact of fringing magnetic fields in a turbulent Rayleigh-B{\'e}nard convection setup, where it was shown that the global heat transport decreases with an increase of fringe-width. The convective motion in regions of strong magnetic fields is confined near the sidewalls. In the second configuration, we numerically study the effects of an oscillating magnetic obstacle with different frequencies of oscillation on liquid metal flow in a duct. The Reynolds number is low such that the wake of the stationary magnetic obstacle is steady. The transverse oscillation of the magnet creates a sinusoidal time-dependent wake reminiscent of the vortex shedding behind solid obstacles. We examine the behavior of the streamwise and spanwise components of the Lorentz forces as well as the work done by the magnets on the fluid. The frequency of the oscillation of the streamwise component of Lorentz force is twice that of the spanwise component as in the case of lift and drag on solid cylindrical obstacles. The total drag force and the energy transferred from the magnets to the fluid show a non-monotonic dependence on the frequency of oscillation of the magnetic obstacle indicative of a resonant excitation of the sinusoidal vortex shedding.