Burnett Theory of Thermal Transpiration with Wall Accommodation

Abstract

Thermal transpiration in a capillary is analyzed by use of second-order Chapman-Enskog constitutive relations for heat flux and stress. Constants of integration are determined by imposing the usual boundary conditions and results for low and for standard pressures. No arbitrary parameters appear, but energy and momentum accommodation coefficients enter in a way which significantly influences the interpretation of experimental data. The theory is worked for polyatomic gases with the result that the total thermal conductivity appears rather than the translational part. The results are compared with the dusty gas model, the Weber-Schmidt equation, and experimental data.