Eur. Phys. J. E (2014) 37: 77
https://doi.org/10.1140/epje/i2014-14077-2

Regular Article

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

¹ Departamento de Física Aplicada I, Universidad Complutense, Plaza de las Ciencias, 1, 28040, Madrid, Spain
² Laboratoire des Fluides Complexes et leurs Réservoirs - UMR5150, Université de Pau et des Pays de l’Adour, 64600, Anglet, France

^* e-mail: jmortizz@fis.ucm.es

Received: 20 June 2014
Accepted: 10 July 2014
Published online: 28 August 2014

Abstract

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.