On coupled heat and moisture transfer in deformable porous-media

The stress-induced flow of interstitial fluid in porous media and the coupled heat-moisture transfer in porous media under gradients of temperature and moisture have been studied extensively as independent phenomena based on Biot's theory and Philip-de Vries theory, respectively. This paper presents a formulation for coupled heat-moisture transfer in deformable porous media in terms of continuum thermo-dynamics and hydrodynamics. It takes into account the coupling effects of temperature gradient and deformations on flow in porous media. Displacements, temperature and volumetric moisture content are used as the basic unknowns primarily. An alternative set of governing equations in which the water pressure is treated as a basic unknown instead of the moisture content is also presented. The present formulation coincides with that of Philip and de Vries when the effects of deformation and liquid-vapour phase transition are omitted completely, while its linearized version reduces to Biot's theory when the effect of thermal expansion is neglected. Comparison between the solution of the present model and that given by Biot is illustrated analytically for a one-dimensional problem which is considered by Biot as an idealization of a standard soil test 1