On the Rheology of Newtonian Single-Phase Multicomponent Mixtures

TL;DR

This paper investigates how diffusive transport mechanisms influence the composition, heat flux, and shear stress in turbulent boundary layers of Newtonian multicomponent gas mixtures, highlighting the importance of species-specific flux balances.

Contribution

It introduces a mathematical model to analyze the effects of diffusive flux balances on fluid properties and flow characteristics in multicomponent mixtures under temperature gradients.

Findings

Non-constant composition profiles can develop due to diffusive flux balances.

Diffusive mechanisms significantly impact wall heat flux and shear stress.

Mathematical modeling reveals the interplay between diffusiophoretic diffusion and temperature gradients.

Abstract

In the turbulent boundary layer of multicomponent fluid mixtures, the species-specific mass flux is determined by the combination of turbulent-diffusiophoretic diffusion and diffusion due to gradients in supplementary fields (e.g. temperature). For inert mixtures, a balance must exist between all the diffusive transport mechanisms so that the net diffusive mass flux normal to the wall is zero everywhere. This may require non-constant composition profiles. Implications are discussed, and mathematical modelling is employed to demonstrate how this may affect fluid property profiles, wall heat flux, and wall shear stress in a Newtonian ternary gas mixture ($H_2 + N_2 + CO_2$) subject to a temperature gradient.