General modeling considerations
Heat Transfer in Porous Media. Phase Change

In view of its particular practical importance, the following section focuses solely on the case of liquid-vapor phase change (evaporation-condensation), while liquid-solid phase change, which is less studied in comparison (although it is involved in many applications: snow melting, metallurgy/foundry, etc.), is not addressed. Let us simply point out that solidification of a multiconstituent mixture involves two mechanisms, dominated by possible instabilities at the fluid/solid interface:

• columnar growth from the cooling surface, leading to the presence of a porous medium ("mushy zone");

• growth of equiaxed grains in the cooling liquid solution.

Porous media" models have therefore been developed.

Readers interested in these issues will find some bibliographical...