Strong nonequilibrium effects on specific heats and thermal conductivity of diatomic gas Original Research Article

The specific heats and thermal conductivity in a diatomic gas with a strong vibrational nonequilibrium are studied starting from the kinetic equations for the distribution functions. Three models for the heat conductivity coefficients are considered. The first one is based on a rigorous kinetic theory treatment. In the second model the inelastic collision integrals are neglected and the thermal conductivity coefficients are expressed only in terms of standard elastic collision integrals and nonequilibrium specific heats. The third model uses the Eucken empirical formula with real gas specific heats. The results are compared with experimental data and with the results of other authors. The limits of the validity of the Eucken formula are estimated and a refinement for strong nonequilibrium is given. A simplified formula for the heat conductivity coefficient is proposed which closely agrees with the experimental data and with the exact kinetic model.