Long-wavelength nonequilibrium concentration fluctuations induced by the Soret effect.
In this paper we evaluate the enhancement of nonequilibrium concentration fluctuations induced by the Soret effect when a binary fluid layer is subjected to a stationary temperature gradient. Starting from the fluctuating Boussinesq equations for a binary fluid in the large-Lewis-number approximation, we show how one can obtain an exact expression for the nonequilibrium structure factor in the long-wavelength limit for a fluid layer with realistic impermeable and no-slip boundary conditions. A numerical calculation of the wave-number dependence of the nonequilibrium enhancement and of the corresponding decay rate of the concentration fluctuations is also presented. Some physical consequences of our results are briefly discussed.
Ortiz de Zárate
José María
JM
Departamento de Física Aplicada I, Facultad de Física, Universidad Complutense, E28040 Madrid, Spain. jmortizz@fis.ucm.es
Fornés
José Antonio
JA
Sengers
Jan V
JV