Stefan Condition

The Stefan condition defines explicitly the velocity of the phase change interface in function of the material density, the heat flux across the interface, and the latent heat of phase change.

It applies to the case of phase change between a solid (or immobile fluid) and fluid phase, with a sharp transition between the phases, and no topology changes.

The Phase Change Interface boundary condition should be used on the boundaries adjacent to both phases domains, to compute the time-dependent location of the phase change interface.

The latent heat of phase change is implicitly taken into account through the definition of the phase change velocity.

The Stefan condition defines the phase change interface velocity vn as follows:

with

the latent heat of phase change from solid to fluid (SI unit: J/kg), ρs the solid density (SI unit: kg/m3), and q the conductive heat flux jump across the interface (SI unit: W/m2), 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.