Behavior of magnetothermal Rayleigh–Benard convection of air visualized by 3D simulations

Abstract

We conducted transient three-dimensional numerical computations to scrutinize the behavior of magnetothermal convections of air created by a steep magnetic gradient, i.e., the magnetic force, in Rayleigh–Benard configuration (a shallow cylindrical enclosure heated from below and cooled from above). First, the behavior of Rayleigh–Benard convection generated by the gravitational buoyant force alone was observed. Second, the behavior of magnetothermal Rayleigh–Benard convections was observed for the different initial conditions and magnetic gradients. In concrete terms, we investigated the behaviors of the enhanced Rayleigh–Benard convection and the suppressed Rayleigh–Benard convection formed by the influences of the magnetic and gravitational buoyant forces. To clarify the effect of the magnetic force alone, we studied the behavior of the magnetothermal convection created in a nongravitational field using different initial conditions. Finally, we compared the computed average Nusselt numbers in both gravitational and nongravitational fields with the classical experimental data for Rayleigh–Benard convection reported by Silveston, by applying the magnetic Rayleigh number first proposed by Braithwaite et al.