The effect of uniform magnetic field on spatial-temporal evolution of thermocapillary convection with the silicon oil based ferrofluid

• Main Authors: Yang Shuo, Ma Rui, Deng Qiaosheng, Wang Guofeng, Gao Yu, Ma Shanshan
• Format: Article
• Language: English
• Published: VINCA Institute of Nuclear Sciences 2020-01-01
• Series: Thermal Science
• Subjects: uniform magnetic field; liquid bridge; level set method; thermocapillary convection
• Online Access: http://www.doiserbia.nb.rs/img/doi/0354-9836/2020/0354-98362000156Y.pdf

A uniform axial or transverse magnetic field is applied on the silicon oil based ferrofluid of high Prandtl number fluid (Pr ≈ 111.67), and the effect of magnetic field on the thermocapillary convection is investigated. It is shown that the location of vortex core of thermocapillary convection is mainly near the free surface of liquid bridge due to the inhibition of the axial magnetic field. A velocity stagnation region is formed inside the liquid bridge under the axial magnetic field (B = 0.3-0.5 T). The disturbance of bulk reflux and surface flow is suppressed by the increasing axial magnetic field. There is a dynamic response of free surface deformation to the axial magnetic field, and then the contact angle variation of the free surface at the hot corner is as following, φhot, B = 0.5 T = 83.34° > φhot, B = 0.3 T = 72.16° > > φhot,B = 0.1 T = 54.21° > φhot, B = 0 T = 43.33°. The results show that temperature distribution near the free surface is less and less affected by thermocapillary convection with the increasing magnetic field, and it presents a characteristic of heat-conduction. In addition, the transverse magnetic field does not realize the fundamental inhibition for thermocapillary convection, but it transfers the influence of thermocapillary convection to the free surface.