Non-equilibrium fluctuations induced by the Soret effect in a ternary mixture

José María Ortiz De Ortiz de Zarate (1) , Cédric Giraudet (2) , Henri Bataller (2) , Fabrizio Croccolo (2)

1 Departamento de Fisica Aplicada [UCM Madrid]
2 LFCR - Laboratoire des Fluides Complexes et leurs Réservoirs

We present, based on fluctuating hydrodynamics, the theory of concentration fluctuations in a ternary mixture subjected to a stationary temperature gradient, so that composition gradients are present due to thermal diffusion (Soret effect). We neglect gravity and confinement (boundary conditions) but consider a completely generic diffusion matrix, including cross-diffusion effects. We find, as in the case of binary mixtures, an important non-equilibrium enhancement of the concentration fluctuations, which is proportional to the square of the gradient and inversely proportional to the fourth power of the fluctuations wave number, q−4. The results of this paper are expected to be asymptotically correct for fluctuations of large q, while for shorter q gravity and confinement effects need to be incorporated. Comparison with previous work in the topic is included. Graphical abstract: [Figure not available: see fulltext.]

Mots clés: Topical Issue: Thermal non-equilibrium phenomena in multi-component fluids

Domaines: Sciences de l'ingénieur [physics]

José María Ortiz De Ortiz de Zarate, Cédric Giraudet, Henri Bataller, Fabrizio Croccolo. Non-equilibrium fluctuations induced by the Soret effect in a ternary mixture. European Physical Journal E: Soft matter and biological physics, 2014, 37 (8), pp.Article number 77, Pages 1-7. ⟨10.1140/epje/i2014-14077-2⟩. ⟨hal-01279149⟩