Coarse-grain model for internal energy excitation and dissociation of molecular nitrogen

Thierry E. Magin, Marco Panesi, Anne Bourdon, Richard L. Jaffe, David W. Schwenke

Research output: Contribution to journalArticlepeer-review


A rovibrational collisional coarse-grain model has been developed to reduce a detailed mechanism for the internal energy excitation and dissociation processes behind a strong shockwave in a nitrogen flow. The rovibrational energy levels of the electronic ground state of the nitrogen molecule were lumped into a smaller number of bins. The reaction rate coefficients of an ab initio database developed at NASA Ames Research Center were averaged for each bin based on a uniform distribution of the energy levels within the bin. The results were obtained by coupling the Master equation for the reduced mechanism with a one-dimensional flow solver for conditions expected for reentry into Earth's atmosphere at 10 km/s. The coarse-grain collisional model developed allow us to describe accurately the internal energy relaxation and dissociation processes based on a smaller number of equations, as opposed to existing reduced models assuming thermal equilibrium between the rotational and translational energy modes.

Original languageEnglish (US)
Pages (from-to)90-95
Number of pages6
JournalChemical Physics
Issue number1
StatePublished - Apr 4 2012
Externally publishedYes


  • Atmospheric entries
  • Chemical mechanism reduction
  • Dissociation
  • Nitrogen flows
  • Rovibrational energy excitation

ASJC Scopus subject areas

  • General Physics and Astronomy
  • Physical and Theoretical Chemistry


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