Convection in the Mushy Zone during Directional Solidification

Abstract

Directional solidification experiments with 26% NH4Cl-H2O solution were carried out to study convection in the mushy layer. Results show that prior to the onset of plume convection, there is no convective motion in the mush, even though there is vigorous finger convection emanating from the mush-liquid interface. After plume convection is fully developed, the flow in the mush is mainly downward, with some lateral feeding into the chimneys, where the upward fluid motion is confined. Further experiments in a Hele Shaw cell revealed interesting behavior of the flow in the chimney.