On the Rheology of Newtonian Single-Phase Multicomponent Mixtures

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.