Effect of a Uniform Axial Magnetic Field on the Spatiotemporal Evolution of Thermocapillary Convection in a High Prandtl Fluid Under Microgravity

In this paper, the semi-floating liquid bridge model with the silicone oil-based ferromagnetic fluid under microgravity was taken as the research object. The enhanced level set method was employed to numerically monitor the free surface flow characteristics, utilizing a staggered grid. The internal flow, temperature, velocity and interface deformation of thermocapillary convection under a uniform axial magnetic field were studied by direct numerical simulation. The results show that the transverse development of thermocapillary convection is suppressed by the axial uniform magnetic field, and the cell flow is controlled near the free surface. The average axial velocity was increased by about three times, and the average radial velocity was increased by about two times. The average axial temperature near the free surface was much higher than that on other radii. The axial temperature level of the surface flow was improved under of the influence of a uniform axial magnetic field. The axial temperature gradient in the central area of the liquid bridge basically showed the same change rule. The closer to the hot disk of the liquid bridge, the larger the axial temperature gradient. In addition, the axial uniform magnetic field effectively suppressed the micro-deformation of the free interface, and the free surface micro-deformation was at an order of magnitude of 10⁻⁵ (the deformation of the free surface in thermocapillary convection within a liquid bridge without a magnetic field was at an order of magnitude of 10⁻⁴). Therefore, studying the influence of the axial magnetic field on the thermocapillary convection of a high Prandtl number fluid can provide the necessary theoretical support for the development of crystal preparation technology.