Modeling Soret coefficient measurement experiments in porous media considering thermal and solutal convection

We address the problem of thermal diffusion in binary fluid mixtures, lying within a porous medium and subjected to a horizontal thermal gradient. Pre liminary numerical results indicate that multiple convection-roll flow patt erns can develop depending on the Soret number value, for counteracting the rmal and solutal buoyancy forces. Investigating solute behaviour, the influ ence of these forces on solute transport is described in detail. Furthermor e, it is shown that the theory represents well the solute behaviour when so lutal buoyancy force is negligible. Finally, reproducing thermogravitationa l experiments by numerical means, dispersion is exhibited as a possible cau se of the observed discrepancy between numerical and experimental results. The influence of dispersion on diffusive and thermal diffusive solute trans ports can be strong. (C) 2001 Elsevier Science Ltd. All rights reserved.