Transport properties of polyatomic gases

Abstract

The paper reviews the current status of the study of the transport properties of polyatomic gases. The experimental techniques which have a proven record of accurate measurement of the viscosity, diffusion coefficient, and thermal conductivity are identified and the extent of available data is briefly discussed. Attention is concentrated upon the measurement of the thermal conductivity since it has proved to be the most difficult property to measure accurately and yet is of the greatest significance in industrial heat-transfer processes. The theoretical description of the transport properties of polyatomic gases is also considered, and the results of the first exact evaluation of the interaction viscosity of a model atom-rigid rotor system are reported. A comparison with the results of approximate, but simpler, calculation schemes reveals a good agreement at sufficiently high temperatures. In contrast, for the thermal conductivity, the same approximation schemes lead to a substantial difference between the calculated values and the experimental observation, even when the approximations are used to evaluate just one parameter. An empirical method of calculation of the same parameter is shown to lead to substantially improved predictions of the thermal conductivity.