Kinetic Theory of Reactive Molecular Gases
Abstract
In high enthalpy gaseous flows associating high velocities and/or high temperatures, physical and chemical processes such as vibrational excitation, dissociation, ionisation and various reactions, can take place. The characteristic times of these processes have often the same order of magnitude as the "mechanical" or aerodynamic characteristic times, so that these flows constitute typical non-equilibrium media. The best way for analysing these reactive flows in continuous or "collisional" regime consists in using a statistical approach by considering the macroscopic quantities as local averages of various properties of elementary particles (molecules, atoms, ions,...) and by taking into account their interactions resulting from their "collisions". Thus, the Boltzmann equation seems to be an appropriate tool for the description of these flows. Among the methods used for solving the Boltzmann equation, the Chapman-Enskog method, consisting in expanding the distribution function in a series of a "small parameter" EI - equal to the ratio of the characteristic time between collisions to a reference flow time has known a great success. However, in the past, it has been generally limited to the case where only one single type of collision is present in the medium. Thus, at relatively low temperature, when the elastic collisions are "dominant", the behaviour of the system is correctly described by Navier-Stokes equations in which transport terms are satisfyingly calculated by the Chapman-Enskog method.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2009
- Accession Number
- ADA567780
Entities
People
- Raymond Brun