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

arXiv eprints
 Pub Date:
 September 2021
 arXiv:
 arXiv:2109.05082
 Bibcode:
 2021arXiv210905082V
 Keywords:

 Physics  Fluid Dynamics;
 Physics  Chemical Physics
 EPrint:
 38 pages, 4 figures