Application of ab-initio based grouped rates for modeling non-equilibrium flow physics

Maitreyee P. Sharma, Simone Venturi, Alessandro Munafò, Marco Panesi

Research output: Chapter in Book/Report/Conference proceedingConference contribution


This work focuses on the use of ab-initio grouped rates obtained from the CG-QCT method and analytical expressions to model non-equilibrium chemical processes in hypersonic flows. The groups are made by dividing the energy spectrum of the molecule into equal energy intervals. The reduced order framework is derived from the multi-group maximum entropy model using a linear reconstruction function. This paper focuses on three different system of molecules which are of interest during reentry into Earth’s atmosphere: (i) (Formula Presented) �collisions, (ii) (Formula Presented) and (Formula Presented) collisions and (iii) (Formula Presented). The grouped rates for the nitrogen systems are obtained using the CG-QCT method considering the full set of ro-vibrational levels of nitrogen molecule whereas analytical expressions are used to compute the grouped rates for the oxygen system. The reduced order model is used in conjunction with CFD codes to predict the non-equilibrium behavior of high speed flows in one and two dimensions. Two different testcases are considered: (i) one-dimensional nozzle flow and (iii) two-dimensional axi-symmetric flow over a sphere. The results are compared to the state-to-state simulation for the oxygen case since we have the state-to-state rates available for vibrational specific processes. We achieve good agreement with the state-to-state results for the non-equilibrium distributions. The strong state of non-equilibrium observed in the results lays emphasis on the need for computationally efficient models to simulated these high-enthalpy flows.

Original languageEnglish (US)
Title of host publicationAIAA Scitech 2019 Forum
PublisherAmerican Institute of Aeronautics and Astronautics Inc, AIAA
ISBN (Print)9781624105784
StatePublished - 2019
EventAIAA Scitech Forum, 2019 - San Diego, United States
Duration: Jan 7 2019Jan 11 2019

Publication series

NameAIAA Scitech 2019 Forum


ConferenceAIAA Scitech Forum, 2019
CountryUnited States
CitySan Diego

ASJC Scopus subject areas

  • Aerospace Engineering

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