State specific modeling of energy transfer in nitrogen shocks using high fidelity models

In the current work, newly-developed MD-QCT reaction and relaxation databases forinteral energy relaxation nitrogen are implemented in DSMC simulations for 0D heat bathcases. In particular, two-dimensional coarse-grained binning method is used to treat thediscrete internal states of N₂ in groups, and it is found that the convergence of bin-basedrelaxation cross sections to state-specific relaxation cross sections is good with approxi-mately 10 bins in the rotational and vibrational modes (99 bins in total). In the 0D heatbath cases for N-N₂ relaxation, it is found that T_r relaxes faster than T_v at relatively lowtemperature and at a very similar rate as T_v at relatively high temperature. However, the Z_r obtained from DSMC are smaller than those obtained directly using the MD method by a factor between 1.3 and 5 at various temperatures, and the Z_v are smaller by a factorof around 6. For N₂-N₂ relaxations, Z_r and Z_v are different even at very high T_t, and the Z_r and Z_v obtained from DSMC are smaller than those obtained directly using the MD method by approximately one order of magnitude.