A BGK model for high temperature rarefied gas flows

Céline Baranger (1) , Gentien Marois (1) , Jordane Mathé (1) , Julien Mathiaud (1) , Luc Mieussens (2)

1 CESTA - Centre d'études scientifiques et techniques d'Aquitaine
2 IMB - Institut de Mathématiques de Bordeaux

High temperature gases, for instance in hypersonic reentry flows, show complex phenomena like excitation of rotational and vibrational energy modes, and even chemical reactions. For flows in the continuous regime, simulation codes use analytic or tabulated constitutive laws for pressure and temperature. In this paper, we propose a BGK model which is consistent with any arbitrary constitutive laws, and which is designed to make high temperature gas flow simulations in the rarefied regime. A Chapman-Enskog analysis gives the corresponding transport coefficients. Our approach is illustrated by a numerical comparison with a compressible Navier-Stokes solver with rotational and vibrational non equilibrium. The BGK approach gives a deterministic solver with a computational cost which is close to that of a simple monoatomic gas.

Mots clés: rarefied gas dynamics; BGK model; polyatomic gas; real gas effect; second principle

Domaines: Mécanique des fluides [physics.class-ph]

Céline Baranger, Gentien Marois, Jordane Mathé, Julien Mathiaud, Luc Mieussens. A BGK model for high temperature rarefied gas flows. 2019. ⟨hal-01722873v2⟩