Comments on “mechanodiffusion in slightly rarefied gas mixture

Cross effects arising in a binary mixture of rarefied gases confined between two infinite plates are studied. The Onsager reciprocity relations for these phenomena have been derived applying general properties of the Boltzmann equation and the boundary conditions for the distribution function. Phenomena taking place only when the upper and lower plates are different have been distinguished. It has been pointed out that the cross effects considered by Vysotsky and Roldughin [Physica A 209 (1994) 25] are not a consequence of the surface accommodation difference of the plates as they assert.