Eur. Phys. J. E 37, 77 (2014)

http://epje.epj.org/articles/epje/abs/2014/08/10189_2014_Article_34/10189_2014_Article_34.html

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

José Maria Ortiz de Zárate, Cédric Giraudet, Henri Bataller, and Fabrizio Croccolo

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.