ANALYSIS OF CHEMISTRY MODELS FOR DSMC SIMULATIONS OF THE ATMOSPHERE OF IO
Open Access
- Author:
- Deng, Hao
- Graduate Program:
- Aerospace Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- None
- Committee Members:
- Dr Deborah A Levin, Thesis Advisor/Co-Advisor
Dr Deborah Levin, Thesis Advisor/Co-Advisor - Keywords:
- Chemistry Model
Io
DSMC
MD/QCT - Abstract:
- Chemical reactions between sulfur dioxide and atomic oxygen are important in modeling the atmosphere of Io and since the atmosphere is sufficiently rarefied, the flow about the Jovian moon is usually modeled using DSMC. The chemical reaction rates between SO2 and O obtained using the Molecular Dynamic/Quasi- Classical Trajectory (MD/QCT) method are compared with the Total Collisional Energy (TCE) model of Bird and values in the literature. The implementa- tion of both MD/QCT and TCE chemistry reaction models in DSMC is studied in a 0-D time dependent analysis and 2-D axisymmetric DSMC simulations. The MD/QCT simulations were found to result in lower reaction rate constants and reaction probabilities than the TCE model and the vibrational favoring feature of the SO2 + O -> SO + 2O reaction was revealed. A 2-D DSMC simulation of an approximate planetary flow consisting of a plume-counter flow between planetary outgassing sulfur dioxide and high energy free stream oxygen was performed. The flow conditions are such that the reference values used in obtaining the total VHS cross section are inadequate to describe the total collisional cross section. Therefore the total cross section using the more general viscosity cross section was obtained through the MD/QCT simulations and was found to have a significantly differ- ent energy dependence compared to the original VHS cross section. For the 2-D DSMC simulations it was found that the structure of the flow as well as the chem- ically formed sulfur oxide were different for the MD/QCT and the TCE reaction probabilities and total cross sections. In addition, the reaction region was found to be highly non-equilibrium, which suggests that MD/QCT is a more suitable chemistry model for the simulation of the Io’s atmosphere.