Physical modeling of simultaneous heat and mass transfer: species interdiffusion, Soret effect and Dufour effect

Abstract In problems involving simultaneous heat and mass transfer there exist coupling between these phenomena: temperature gradient may cause mass flux (Soret effect) and concentration gradient may cause heat flux (species interdiffusion and Dufour effect). In a large number of scientific works the authors do not include these effects into their models, without providing any justifications. In this paper we model natural convection inside a two-dimensional square cavity having evaporation and condensation boundary conditions. All coupling effects are taken into account and their relative impacts on numerical solutions are accurately assessed. Numerical results demonstrate that the species interdiffusion phenomenon has to be taken into account in order to guarantee the energy conservation in the domain. The influence of Soret and Dufour effects is examined and it is shown that for a binary mixture of steam and air these two effects have negligible contribution. We point out, however, that for some circumstances involving large thermal diffusion ratios Dufour effect may become important.