Authors: Mouhamadou A. Diop, Chen Xiaomeng and Mohamed I. Hassan
Abstract: Molten metallic flow in metallurgical plant is highly turbulent and presents a complex coupling with heat transfer, phase change, chemical reaction, momentum transport, etc. Molten silicon flow condition has significant effect on its multicrystalline directional solidification, where flow characteristics are affecting the temperature field and the emerging crystallization interface as well as the species transport and impurities distribution during the casting process. Because of the complexity and limits of reliable measuring techniques, computational fluid dynamics (CFD) models are useful tools to study and quantify these challenges. The main goal of this study is to investigate the potential of introducing magnetic field for controlling the molten silicon flow prior to casting. A multidimensional numerical model is developed for predicting the interaction among the Lorentz force, molten metal flow, and the related transport phenomenon including variable material properties. The developed numerical model is used to study the effects of the applied magnetic force on the molten flow behavior. In this paper, coupled and decoupled, steady and unsteady models of molten flow and crystallization interface are compared. Our numerical model was tested for numerical accuracy and correctness by using analytical solutions. To validate the physical model, such as a local molten silicon flow influenced by buoyancy and Lorentz forces, a physical model with a low melting point metallic alloy in a traveling magnetic field was developed. A simplified global thermal model of a crystallization furnace shows that mainly the thermal conductivities of the silicon and the crucible as well as the heating and cooling powers determine the temperature gradients in the molten metal and the crystallization interface.
Keywords: numerical simulation, solidification, Multicrystalline, traveling Magnetic field.