Low prandtl number convection in a vertical cavity: effect of aspect ratio and suppression of oscillations by an axial magnetic field

摘要

Natural convection of a low Prandtl number liquid, (Pr chemical bounds 0.015), under the influence of an axial magnetic field inside a differentially-hheated rectangular enclosure has been umerically studied. The aspect ratio of the cavity (height/width) is varied from 0.2 to 15 and the Hartmann number is changed from 0 to 100. The degree to which the applied magnetic field suppresses covective motions is extensively studied. In tall cavities, under weak magnetic fields, the flow may become oscillatory and shows random behavior at high Grashor numbers, Gr chemical gounds 10~6, used in the present study. This has never been reported before. A sufficiently strong magnetic field suppresses these oscillations. The effect of aspect ratio on the average Nusselt number under various strengths of the magnetic field is graphically illustrated.