The Phase Change Interface boundary condition is applicable on the boundaries located at the interface between a solid and a fluid domain, two solid domains, two fluid domains or two porous medium domains.
The Phase Change Interface, Exterior boundary condition is applicable on the exterior boundaries adjacent to a solid, fluid, or porous medium domain.
with Ls → f the latent heat of phase change from solid to fluid (SI unit: J/kg),
ρs the solid density (SI unit: kg/m
3), and
q the conductive heat flux jump across the interface (SI unit: W/m
2), defined as
with ks the solid thermal conductivity (SI unit: W/(m·K)),
kf the fluid thermal conductivity (SI unit: W/(m·K)), and
Ts,
Tf the temperatures on each side of the interface.
The phase change velocity vn appearing in Stefan condition is relative to the solid position. In case of translation of the solid (using
Translational Motion subfeature under
Solid with Translational Motion feature for instance), as in a continuous casting process, the solid translation velocity
us contributes to
vn to describe the interface velocity relative to the spatial frame: