Evaluation of the Transport Coefficients in Polyatomic Gases:
Cases of the Variable Soft Sphere and Lennard Jones Potential Models
Djamel Omeiri and Djamel E. Djafri
In this work, using the Variable Soft Sphere (VSS) molecular model and the Lennard-Jones (12–6) intermolecular potential model, various transport coefficients are calculated and compared. We use the kinetic model of Gross-Jackson to derive analytical expressions for the binary-diffusion and thermal-diffusion coefficients for the VSS model and evaluate them for an Ar-N2 mixture. These coefficients are calculated numerically for the Lennard-Jones (12–6) potential. The various contributions to these coefficients are discussed in detail. Overall, it is found that there is a fairly good agreement between the two models except for the thermal-diffusion coefficient where we found important discrepancies at temperatures above 6000 K. We also calculate the thermal conductivity coefficient of N2. Here again, there is a good agreement between the two models up to 3000 K, but the discrepancies become increasingly important at high temperatures.
Keywords: Transport coefficients, Variable Soft Sphere, Lennard-Jones potential