Non-isothermal rarefied gas flow through a slit

A rarefied gas flow through a thin slit caused by small drops of the pressure and temperature is studied on the basis of the kinetic equation. The linearized S-model equation is solved numerically by the discrete velocity method. The gas–surface interaction is assumed diffuse-specular. As a result four kinetic coefficients have been calculated: the mass flow rate caused by the pressure drop WP, the mass flow rate caused by the temperature drop WT, the heat flux caused by the pressure drop QP, and the heat flux caused by the temperature drop QT. It is shown that only the coefficient WP very weakly depends on the gas–surface interaction parameter α. The rest of the coefficients, i.e., WT, QP, and QT, significantly depend on the parameter α. The Onsager relation WT=QP is numerically confirmed. An analysis of the thermomolecular pressure effect on the slit is given.