Double-Diffusive Convection on the Solid-Liquid Interface in the Early Stage of Solidification

Abstract

In the present study, we report on the effect of double diffusive convection associated with solute discharge in the early stage of unidirectional solidification from above. Two-dimensional numerical simulations have been conducted to clarify the concentration, temperature and heat flux on the solid-liquid interface under a constant solid layer growth rate. The moving boundary due to solid layer growth was formulated according to the boundary tracking method. The simulations were conducted by varying the initial conditions; concentration, solid layer growth rate and heating temperature at the bottom. The effects of thermal and solutal Rayleigh number on the concentration and the convective heat flux at the solid-liquid boundary were discussed, and the associated correlations to predict those values as functions of the initial thermal and solutal Rayleigh numbers as well as the speeds of solidification were derived.