Conductive heat transfer
Heat transfer in porous media

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. It is then possible to define the effective thermal conductivity λ* using a relationship giving the heat flux density vector $\overrightarrow{\varphi }$ as a function of the thermal gradient analogous to Fourier's law for homogeneous media, i.e. :