Comparison of Sound Dispersions in Rarefied Carbon Dioxide and Nitrogen Gases

Numerical predictions are made for the sound dispersion in rarefied carbon dioxide (CO2) and nitrogen (N2) gases using the Navier-Stokes equation and the method of equivalent heat capacity theory. Translational dispersion, rotational dispersion, and vibrational relaxation dispersion were individually analyzed to compare their contributions to the total dispersion across various frequency ranges. It is observed that at low frequencies, the dispersion in CO2 is greater than that in N2, with vibrational dispersion dominating. Conversely, at high frequencies, the dispersion in CO2 is less than that in N2, with translational and rotational dispersion taking the lead.