Modeling of OH product distributions using QCT-MD and BL models in a bow shock

The quasiclassical trajectory (QCT) method enables one to obtain reaction probabilities and cross sections for fundamental reactions and to simulate strongly nonequilibrium flows. We examine the formation of vibrationally hot OH for a rarefied flow about a sphere at 80 and 100 km altitudes using the direct simulation Monte Carlo (DSMC) method. The main objective is to apply new chemistry models in the DSMC simulations of OH formation mechanisms in hypersonic flows at high altitudes. Using a parallel MD code, we calculate the reaction cross sections and OH product rotational and vibrational distributions for H + O₂ → OH + O exchange reaction, as well as the post-collisional OH internal modes. The reaction probabilities are used in a DSMC computational tool to study the H+O₂ exchange reaction, the main OH production mechanism at 100 km altitude. Approximately an order of magnitude difference is observed between the MD and TCE rates, and differences in the predicted vibrational OH temperature were also obtained.