Kinetic Theory of Thermal Transpiration and Mechanocaloric Effect. I

Abstract

A general kinetic theory analysis of the cross phenomena of thermal transpiration and the mechanocaloric effect is presented. The Onsager reciprocal relations are verified and the mass flux and the heat flux are expressed in terms of the stationary values of appropriate variational functionals. These considerations are valid for the linearized Boltzmann equation with general forms of the boundary conditions and a capillary of arbitrary shape. It is felt that some of the work reported here should be of general interest in that similar considerations could be used for a study of other cross effects. Some explicit numerical results are given for the case of parallel plates by using the BGK model and assuming diffuse reflection at the surface.