3. Conductive heat transfer

3.1 Concept of effective thermal conductivity

If, under the action of a temperature gradient applied to a porous medium saturated by a single phase, the saturating non-reactive fluid remains stationary, heat transfer within the porous medium is purely conductive, which is the case for heat transfer in microgravity. This purely conductive situation is also found in the case of heat transfer in a purely solid composite medium, and some of the results for these media are incorporated into the analysis presented in this paragraph. It is possible to define the effective thermal conductivity ${\lambda }^{*}$ using a relationship giving the heat flux density vector...