Monte Carlo simulation of nitrogen dissociation based on state-resolved cross sections

Abstract

State-resolved analyses of N + N2 are performed using the direct simulation Monte Carlo (DSMC) method. In describing the elastic collisions by a state-resolved method, a state-specific total cross section is proposed. The state-resolved method is constructed from the state-specific total cross section and the rovibrational state-to-state transition cross sections for bound-bound and bound-free transitions taken from a NASA database. This approach makes it possible to analyze the rotational-to-translational, vibrational-to-translational, and rotational-to-vibrational energy transfers and the chemical reactions without relying on macroscopic properties and phenomenological models. In nonequilibrium heat bath calculations, the results of present state-resolved DSMC calculations are validated with those of the master equation calculations and the existing shock-tube experimental data for bound-bound and bound-free transitions. In various equilibrium and nonequilibrium heat bath conditions and 2D cylindrical flows, the DSMC calculations by the state-resolved method are compared with those obtained with previous phenomenological DSMC models. In these previous DSMC models, the variable soft sphere, phenomenological Larsen-Borgnakke, quantum kinetic, and total collision energy models are considered. From these studies, it is concluded that the state-resolved method can accurately describe the rotational-to-translational, vibrational-to-translational, and rotational-to-vibrational transfers and quasi-steady state of rotational and vibrational energies in nonequilibrium chemical reactions by state-to-state kinetics.

Rovibrational Energy Transitions and Coupled Chemical Reaction Modeling of H+H2and He+H2in DSMC

“…In comparisons of the transition probabilities between the sections and VHS model, the difference is only produced by the difference o and 6 affects the total cross section in heavy-particle collisions and the total cross section is mostly dependent on the vibrational states of the molecule. In the previous thermochemical nonequilibrium studies of N 2 , the same result was also observed in that the state-specific total cross sections of N 2 are mostly depend on the vibrational states [19].…”

“…(7) and (8), 6 dependent on the vibrational states of the molecule. In the previous thermo studies of N 2 , the same result was also observed in that the state-specific tota mostly depend on the vibrational states [19].…”

“…This is because at highly excited states, the internuclear distance of the colliding molecules increases and significantly influences the total cross section. The statespecific total cross sections to overcome the limitations of the previous total cross section models were initially proposed for the N 2 nonequilibrium work by Kim and Boyd [19]. In this work, it was shown that the state-specific total cross section can accurately describe the thermochemical nonequilibrium of N 2 in comparing with the results of the VHS and VSS models.…”

“…Detailed description about the state-specific total cross sections are provided in the work by Kim and Boyd [19]. In the present work, Eqs.…”

“…In this work, the state-to-state cross sections were obtained from the atomistic calculations of QCT method based on the complicated potential energy surfaces [20,21]. The bound-bound and bound-free transition probabilities of the VHS model are determined as [19].…”