A continuum model for momentum, heat and species transport in binary solid-liquid phase change systems—II. Application to solidification in a rectangular cavity

Abstract

A newly developed continuum model has been used with a well-established control-volume-based, finite-difference scheme to investigate solidification of a binary, aqueous ammonium chloride solution in a rectangular cavity. Advective transport of water enriched interdendritic fluids across the permeable liquidus interface has been identified as the primary mechanism for macroscopic species redistribution. The extent of this penetration is governed by the relative strengths of solutally driven mushy region flows and thermally driven flows in the bulk liquid. Unstable and double-diffusive conditions which accompany the discharge of interdendritic fluids into the liquid core have been shown to result in localized growth rate variations, remelting, and fluctuating bulk fluid transport behavior.