Heavy Particle Impact Vibrational Excitation and Dissociation Processes in CO₂

A heavy particle impact vibrational excitation and dissociation model for CO₂ is presented. This state-to-state model is based on the forced harmonic oscillator (FHO) theory, which is more accurate than current state-of-the-art kinetic models of CO₂ based on first-order perturbation theory. The first excited triplet state ³B₂ of CO₂, including its vibrational structure, is considered in our model, and a more consistent approach to CO₂ dissociation is also proposed. The model is benchmarked against a few academic zero-dimensional (0D) cases and compared to decomposition time measurements in a shock tube. Our model is shown to have reasonable predictive capabilities, and the CO₂ + O ↔ CO + O₂ reaction is found to have a key influence on the dissociation dynamics of CO₂ shocked flows, warranting further theoretical studies. We conclude this study with a discussion on the theoretical improvements that are still required for a more consistent analysis of the vibrational/dissociation dynamics of CO₂.