Steady-state mushy layers: experiments and theory.

A new facility has been developed to investigate the directional solidification of\ud transparent aqueous solutions forming mushy layers in a quasi-two-dimensional\ud system. Experiments have been conducted on NaCl–H2O solutions by translating\ud a Hele-Shaw cell at prescribed rates between fixed heat exchangers providing\ud a temperature gradient of approximately 1 ◦Cmm−1. The mush–liquid interface\ud remained planar at all freezing velocities larger than 8 μms−1, while steepling occurred\ud at lower velocities. No significant undercooling of the mush–liquid interface was\ud detected at freezing velocities up to 12 μms−1. Mathematical predictions of the steadystate\ud temperature profile and mushy-layer thickness as functions of freezing rate are\ud in excellent agreement with experimental measurements