Abstract: Through numerical simulation on a full floating-zone, the characteristics of thermocapillary convection in the melt are studied at different radiation heating temperatures under the rotating magnetic fields (RMF). The Lorentz force induced by the applied RMF under 1mT with 50Hz is not sufficient to effectively control the thermocapillary flow. In this case, the thermocapillary flow presents a rotating oscillatory three-dimensional convection with an oscillatory frequency decreasing with radiation temperature and varying linearly with Ma number. The temperature field in the melt has a 2-D steady axisymmetric distribution which is mainly determined by the diffusion effect when the Ma number is relatively small. However, at the relatively large Ma number, the temperature of the melt is influenced by flow and exhibits periodic oscillation with the same frequency of melt convection. By fixing RMF frequency at 50Hz and increasing the magnetic field intensity, the flow in melt turns into a quasi-2D rotating axisymmetric flow from a 3D periodic oscillatory convection. Accordingly the thermocapillary convection presents a mirror-symmetry structure about the middle plane. Both the temperature and velocity fluctuation in the melts with Ma=21.8,32.9,and 43.7 are effectively suppressed under 2, 3, and 5mT RMFs, respectively.

Key words: floating zone technique, thermocapillary convection, interfacial tension, numerical simulation, rotating magnetic field