The effect of aspect ratio and axial magnetic field on thermocapillary convection in liquid bridges with a deformable free-surface

Abstract

Three-dimensional numerical simulations are performed to analyze the effect of the aspect ratio Ar and axial magnetic field on thermocapillary convection in liquid bridges with deformable free-surface under microgravity, in which the volume of fluid (VOF) method is adopted to track the free-surface movement. The simulation results elucidate that the oscillation wave number m and frequency of temperature fluctuation decrease with increasing Ar, while the amplitude of temperature fluctuation increases with increasing Ar. The deformation ratio ξ of the free-surface increases as Ar increases. The numerical results also reveal that the axial magnetic field causes a concentration of convection vortexes near the free-surface and effectively suppresses the flow in both the radial and axial directions. Moreover, the axial magnetic field effectively damps free-surface deformation, so that the deformation ratio ξ decreases as the Hartmann number Ha increases. The temperature displays a uniform and linear distribution along the free-surface and the axis of molten zone when Ba = 0.3 T.

Keywords

• thermocapillary convection
• deformable free-surface
• microgravity
• VOF
• axial magnetic field