= Salt rejection
{title2=$-D C_x(a^+,t)=\dot a C_i$}
When salt-free <ice> forms from a saline liquid, the moving <phase boundary> excludes the dissolved salt. With equal phase <mass densities>, no bulk flow, liquid salt <diffusion coefficient> $D$, and interface <concentration> $C_i$, salt conservation gives the displayed condition, where $x$ increases from solid to liquid. Positive freezing speed $\dot a$ therefore requires a negative liquid <concentration> <gradient>. During melting the same condition gives dilution. Coupling <salt rejection>, the <liquidus>, and the <Stefan condition> produces the <saline Stefan problem>.
Back to article page
