An ES-BGK model for vibrational polyatomic gases

TL;DR

This paper introduces an extended ES-BGK model for vibrational polyatomic gases that accurately captures energy relaxation and thermodynamic properties while maintaining computational efficiency.

Contribution

It develops a new ES-BGK model incorporating vibrational energy levels, satisfying an H-theorem and allowing flexible parameter fitting for Prandtl number and relaxation times.

Findings

Model satisfies an H-theorem.

Allows fitting arbitrary Prandtl numbers.

Reduces to a computationally efficient three-distribution system.

Abstract

We propose an extension of the Ellipsoidal-Statistical BGK model to account for discrete levels of vibrational energy in a rarefied polyatomic gas. This model satisfies an H-theorem and contains parameters that allow to fit almost arbitrary values for the Prandtl number and the relaxation times of rotational and vibrational energies. With the reduced distribution technique , this model can be reduced to a three distribution system that could be used to simulate polyatomic gases with rotational and vibrational energy for a computational cost close to that of a simple monoatomic gas.