NUMERICAL STUDY OF BUOYANCY-DRIVEN CONVECTION OF MOLTEN GALLIUM UNDER MAGNETIC FIELD

摘要

This paper focuses on the convection of molten gallium contained in an enclosure of aspect ratios 5:1:1.3 subject to horizontal temperature gradient and an external constant magnetic field. Flows without magnetic field are also solved for comparisons by the spectral method. Steady flows and oscillatory flows show different flow structures. The symmetries are strictly maintained for steady flow and the symmetries are broken for oscillatory flow. Near the onset, stable periodical oscillations appear and the symmetries are satisfied between the present state and the state half a period later, which agrees well with the analytical results. The phase characters agree well with the experimental results. Energy analysis shows that the production of fluctuating kinetic energy by shear of mean flow is the main production to the change of the total fluctuating kinetic energy, while viscous effects give the main dissipation term. The dissipation of the fluctuating kinetic energy by magnetic field keeps negative.