Sensitivity analysis and uncertainties quantification on a DSMC code with chemical reactions

The in-house Direct Simulation Monte Carlo code (DSMC-IEMC) has been used in Ariane group for more than 30 years to simulate rarefied gas dynamics in hypersonic conditions. In order to improve the accuracy of the simulations, chemical reactions have been implemented. Considering chemical reactions in the DSMC-IEMC code implies new input data taken into account. Among these parameters, the rotational and vibrational relaxation number, and the Arrhenius coefficients of chemical reactions are now needed to compute the simulation. These parameters are usually chosen to better reproduce the physics of the computation. Some comparison with experimental data can be made to define their values. However, it often remains an uncertainty in their choice. Considering the 2D Cylinder test case with chemical reactions, the aim of this work is to quantify the influence of the different models (relaxation process, chemical models) available in the DSMC-IEMC code and of their main parameters in order to analyze the changes due to the implementation of chemical models in a DSMC code. After the verification of the Total Collision Energy (TCE) chemical model and of the differently weighted molecules scheme for the 2D Cylinder test-case, a sensibility analysis is driven using a generalized Polynomial Chaos.