Monte Carlo calculations of diatomic molecule gas flows including rotational mode excitation
Abstract
The direct simulation Monte Carlo method was used to solve the Boltzmann equation for flows of an internally excited nonequilibrium gas, namely, of rotationally excited homonuclear diatomic nitrogen. The semiclassical transition probability model of Itikawa was investigated for its ability to simulate flow fields far from equilibrium. The behavior of diatomic nitrogen was examined for several different nonequilibrium initial states that are subjected to uniform mean flow without boundary interactions. A sample of 1000 model molecules was observed as the gas relaxed to a steady state starting from three specified initial states. The initial states considered are: (1) complete equilibrium, (2) nonequilibrium, equipartition (all rotational energy states are assigned the mean energy level obtained at equilibrium with a Boltzmann distribution at the translational temperature), and (3) nonequipartition (the mean rotational energy is different from the equilibrium mean value with respect to the translational energy states). In all cases investigated the present model satisfactorily simulated the principal features of the relaxation effects in nonequilibrium flow of diatomic molecules.
 Publication:

NASA STI/Recon Technical Report N
 Pub Date:
 January 1976
 Bibcode:
 1976STIN...7615408Y
 Keywords:

 Diatomic Gases;
 Gas Flow;
 Molecular Rotation;
 Monte Carlo Method;
 Boltzmann Distribution;
 Computerized Simulation;
 Flow Distribution;
 Uniform Flow;
 Fluid Mechanics and Heat Transfer