Numerical simulation of Marangoni effect on the deformation behavior and convection of electromagnetic levitated silicon droplets under static magnetic fields

Abstract

The application of electromagnetic levitation for the measurement of thermophysical properties, container-less processing of materials and evaluation of metallurgical reactions, can be adversely affected by instability phenomena, such as droplet oscillation, deformation and ejection. In this work, the influence of the Marangoni effect and static magnetic fields on the deformation, flow velocities and temperature profiles of electromagnetic levitated silicon droplets are investigated by a series of numerical simulations based on the Arbitrary Lagrangian-Eulerian method. According to the results, in the absence of a static magnetic field, droplet deformation is increased when the Marangoni effect is taken into account. Static magnetic fields can partially restrain droplet deformation and the restraining effect is enhanced by the Marangoni effect. For a silicon droplet of 4mm radius, when a static magnetic field of 1T was added and the Marangoni effect was taken into account, the maximum deformation ratio decreased from 1.413 to 1.373. In the absence of the Marangoni effect, the ratio only decreased from 1.372 to 1.352. In addition, within the droplet, the 1T axial static magnetic field has a significant suppression effect on the internal flow while the velocity near the droplet surface is substantially reduced. Under these conditions, the heat transfer mode changes from convection to conduction. Based on the findings from this work, operational parameters can be optimized in order to improve the stability and deformation behavior of levitated materials.