Molecular dynamics based chemistry models of hypervelocity collisions of O(3P) + SO2(X, 1A1) in DSMC

Abstract

A significant process in the formation of the unique atmosphere of Io, a Jovian moon, is collision-induced dissociation of sulfur dioxide. The direct simulation Monte Carlo method (DSMC) is used to model the rarefied gas dynamics of the Ionian atmosphere. However, there is a lack of reliable reaction and collision cross sections needed for hypervelocity conditions. In this work, collisions between SO2 and O were studied using molecular dynamics/quasi-classical trajectories methods with the potential of Murrell and a force field for reactive systems (ReaxFF). Dissociation to SO was found to be the significant reacting process, but at higher collision energies, complete atomization of SO2 was found to frequently occur. In contrast, dissociation to O2 was found to be mostly negligible and formation of SO3 occurred only at low impact velocities. The chemistry and collision models developed from the Murrell and ReaxFF methods were implemented in DSMC simulations and compared to the baseline DSMC collision and reaction models. It was found that the selection of both the dissociation reaction cross section and the non-reactive collision model has a significant effect on the counterflow, shock gas dynamic structure. © 2013 American Institute of Physics.