Numerical Analysis of Double-Diffusive Convection/Solidification Under g-Jitter/Magnetic Fields

摘要

A finite element model is presented for the g-jitter induced double-diffusive convection and solidification phenomena with and without the presence of magnetic fields in an Sn-doped Bi crystal growth system planned for space experiments. The model is developed based on the deforming finite element formulation with the penalty formulation for pressure approximation. An isothermal front tracking algorithm is used to predict the solid-liquid interface. Extensive numerical simulations are carried out and parameters studied include the solute concentration dependent melting temperature and magnetic field strength under both steady state and g-jitter conditions. Both synthesized g-jitter and real g-jitter data taken from space flights are used. Computed results show that the concentration effects on interface morphology must be considered for an accurate prediction of solidification interface morphology, and g-jitter can induce significant convective flows in the liquid pool, which, in turn, cause solute concentration nonuniformity during the space crystal growth. The use of an applied magnetic field can be effective in suppressing the deleterious g-jitter induced convection and solute nonuniformity and their effects on solidification.