Do thermal diffusion and Dufour coefficients satisfy Onsager’s reciprocity relation?
LOMA, Université de Bordeaux & CNRS, 351 cours de la Libération, 33405, Talence, France
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Revised: 15 September 2014
Accepted: 1 October 2014
Published online: 27 October 2014
It is commonly admitted that in liquids the thermal diffusion and Dufour coefficients DT and DF satisfy Onsager’s reciprocity. From their relation to the cross-coefficients of the phenomenological equations, we are led to the conclusion that this is not the case in general. As illustrative and physically relevant examples, we discuss micellar solutions and colloidal suspensions, where DT arises from chemical reactions or viscous effects but is not related to the Dufour coefficient DF. The situation is less clear for binary molecular mixtures; available experimental and simulation data do not settle the question whether DT and DF are reciprocal coefficients.
Key words: Topical Issue: Thermal non-equilibrium phenomena in multi-component fluids
© EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg, 2014