Ultrahigh Mach number re-entry vehicles create sufficiently energetic flow conditions with substantial ionization occurring in the noncontinuum flow regime. To model these noncontinuum, ionized, and thermochemically nonequilibrium flows, a direct simulation Monte Carlo (DSMC) approach is investigated. Energy exchange models that have been developed for Navier-Stokes computational fluid dynamics computations are examined and revised for application to the DSMC method. Since the electron-heavy particle collision rate is approximately two orders of magnitude higher than that between heavy particles, a new model is developed for electron scattering collision processes and electron-vibrational energy exchange based on the electron-molecule shape resonance phenomena. It is found that the flow electron and vibrational temperatures are sensitive to the electron-vibrational relaxation model because the relaxation time changes by orders of magnitude. The DSMC calculations of the bow-shock region of a blunt body were found to predict the correct flow features for free stream Knudsen numbers spanning the near-free molecular to the continuum limit. The range of degree of ionization was found to vary from the highest altitude to the lowest from 1% to 11%.
|Original language||English (US)|
|Journal||Physics of fluids|
|State||Published - Apr 2008|
|Event||Symposium of the International Union of Theoretical and Applied Mechanics on Recent Advances in Multiphase Flows: Numerical and Experimental, IUTAM - Istanbul, Turkey|
Duration: Jun 11 2007 → Jun 14 2007
ASJC Scopus subject areas
- Condensed Matter Physics