Numerical comparison between the Boltzmann and ES-BGK models for rarefied gases

✍ Scribed by Pierre Andries; Jean-François Bourgat; Patrick le Tallec; Benoit Perthame

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 782 KB
• Volume: 191
• Category: Article
• ISSN: 0045-7825
• DOI: 10.1016/s0045-7825(02)00253-0

✦ Synopsis

Rarefied gas flows obey the Boltzmann equation, but numerical simulations of this equation are not always possible, so that simpler models have been introduced. The ES-BGK equation is one of these models. It gives the correct transport coefficients for the Navier-Stokes approximation, so that Boltzmann or ES-BGK simulations are expected to give the same results for dense gases, but in the case of a rarefied flow, complete numerical comparisons are needed.

In this paper we present numerical comparisons between the two models in transitional regimes (where the ES-BGK model is expected to be useful) for reentry flows around a compression ramp and a plate. We also emphasize that the ES-BGK model gives flow predictions closer to the Boltzmann result than the simpler BGK model.