Consolidated theory of fluid thermodiffusion

We present the Onsager–Stefan–Maxwell thermodiffusion equations, which account for Soret and Dufour effects in multicomponent fluids. Unlike transport laws derived from kinetic theory, this framework preserves structure of isothermal Stefan–Maxwell separating thermodynamic forces that drive diffusion force drives heat flow. The transport-coefficient matrix is symmetric, second law thermodynamics imbues it with simple spectral characteristics. This new approach allows to be considered as a pseudo-species proves equivalent both intuitive extension Fick's generalized equations popularized by Bird, Stewart, Lightfoot. A general inversion process facilitates unique formulation flux-explicit relative any choice convective reference velocity. diffusivities thermal factors are tabulated gaseous mixtures containing helium, argon, neon, krypton, xenon. deployed perform numerical simulations steady three-dimensional ternary gas.