Investigation of dissociation phenomena in Nonequilibrium shock layers

The present work addresses the study of dissociation phenomena in nonequilibrium shock layers. The starting point is the quantum chemistry database, developed at NASA Ames Research Center, providing thermodynamic and state-to-state kinetics data for the rovibrational excitation and dissociation of the nitrogen molecule in its electronic ground-state. The NASA Ames database is used to construct two families of coarse-grained models: i) a vibrational collisional model and ii) an energy bin model. In both cases, the distribution of the energy levels within each vibrational state (bin) is assumed to be Boltzmann at its own temperature. Applications consider inviscid nonequilibrium flows behind normal shock waves. The results show that both the vibrational collisional and the energy bin models lead to an accurate description of dissociation, with the energy bin model requiring the use of only 3 bins. Furthermore, the proposed coarse-grained models provide a superior description of the nonequilibrium phenomena occurring in shock heated flows when compared with conventional multi-temperature models and with coarse-grained models previously developed.