Is Soret equilibrium a non-equlibrium effect?

Alois Würger (1)

1 LOMA - Laboratoire Ondes et Matière d'Aquitaine

Recent thermophoretic experiments on colloidal suspensions revived an old debate, namely whether the Soret effect is properly described by thermostatics, or necessarily requires nonequilibrium thermodynamics. Based on colloidal transport theory and the entropy production of the related viscous flow, our analysis leads to the conclusion that the equilibrium approach may work for small ions, yet fails for colloidal particles and polymers. Regarding binary molecular mixtures, our results shed some doubt on the validity of thermostatic approaches that derive the Soret coefficient from equilibrium potentials.

Mots clés: Thermal diffusion; Soret coefficient; Non-equilibrium thermodynamics; Out-of-equilibrium systems; Onsager theory

Domaines: Matière Molle [cond-mat.soft]

Alois Würger. Is Soret equilibrium a non-equlibrium effect?. Comptes Rendus Mécanique, 2013, 341, pp.438-448. ⟨10.1016/j.crme.2013.02.006⟩. ⟨hal-00837587⟩