DSMC-CFD comparison of a high altitude, hypersonic reentry flow using the Mott-Smith model

T. Ozawa, I. Nompelis, D. A. Levin, M. Barnhardt, G. V. Candler

Research output: Contribution to journalConference articlepeer-review

Abstract

Stardust reentry flows have been simulated at 80 km altitude, 12.8 km/s, using the direct simulation Monte Carlo (DSMC) and computational fluid dynamics (CFD). Neutral and ionization processes among neutral air species, as well as five ionic species and electrons were considered in the DSMC flowfleld modeling using the ion-averaged velocity model to maintain charge-neutrality. In CFD, two electron temperature models were compared, and it was found that the degree of ionization (DOI) is sensitive to the electron temperature model. At 80 km, the DOI predicted by DSMC was found to be approximately 3 %, but in CFD, the DOI is greater than 20 % for the case of T e = T tr and 9 % for the case of T e = T vib, Therefore, compared to the DSMC solution, the assumption of T e = T vib, is preferable in CFD. Using the Mott-Smith (M-S) model, good agreement was obtained between the analytical bimodal distribution functions and DSMC velocity distributions. An effective temperature correction in the relaxation and chemical reaction models using the M-S model was developed in CFD, and the model reduced the continuum breakdown discrepancy between DSMC and CFD inside the shock in terms of DOI and temperatures. With the M-S model, the DOI for the case of T e = T vib, in CFD is decreased by approximately 3%.

Original languageEnglish (US)
Pages (from-to)760-765
Number of pages6
JournalAIP Conference Proceedings
Volume1084
StatePublished - Apr 13 2009
Event26th International Symposium on Rarefied Gas Dynamics, RGD26 - Kyoto, Japan
Duration: Jul 20 2008Jul 25 2008

Keywords

  • Breakdown
  • CFD
  • DSMC
  • Hypersonic
  • Mott-Smith
  • Reentry
  • Stardust

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