Bulk viscosity of dilute gases and their mixtures

TL;DR

This paper uses the Green-Kubo method to analyze the bulk viscosity of dilute gases and their mixtures, focusing on atomic mass effects and gas composition variations, including nitrogen, oxygen, and noble gases.

Contribution

It provides new estimates of bulk viscosity for various gas mixtures and isotopes, expanding understanding of how composition influences bulk viscosity in dilute gases.

Findings

Bulk viscosity varies with atomic mass and gas mixture composition.

Addition of noble gases affects the bulk viscosity of nitrogen.

The study offers detailed bulk viscosity values for nitrogen-oxygen mixtures.

Abstract

In this work, we use the Green-Kubo method to study the bulk viscosity of various dilute gases and their mixtures. First, we study the effects of the atomic mass on the bulk viscosity of dilute diatomic gas by estimating the bulk viscosity of four different isotopes of nitrogen gas. We then study the effects of addition of noble gas on the bulk viscosity of dilute nitrogen gas. We consider mixtures of nitrogen with three noble gases, viz., neon, argon, and krypton at eight different compositions between pure nitrogen to pure noble gas. It is followed by an estimation of bulk viscosity of pure oxygen and mixtures of nitrogen and oxygen for various compositions. In this case, three different composition are considered, viz., 25\% N$_2$ + 75\% O$_2$, 50\% N$_2$ + 50\% O$_2$, and 78\% N$_2$ + 22\% O$_2$. The last composition is aimed to represent the dry air. A brief review of works that study the effects of incorporation of bulk viscosity in analysis of various flow situations has also been provided.