Université de Fribourg

Static versus dynamic analysis of the influence of gravity on concentration non-equilibrium fluctuations

Croccolo, Fabrizio ; Bataller, Henri ; Scheffold, Frank

In: The European Physical Journal E, 2014, vol. 37, no. 11, p. 1–5

In a binary fluid mixture subject to gravity and a stabilizing concentration gradient, concentration non-equilibrium fluctuations are long-ranged. While the gradient leads to an enhancement of the respective equilibrium fluctuations, the effect of gravity is a damping of fluctuations larger than a “characteristic” size. This damping is visible both in the fluctuation power spectrum probed by...

Université de Fribourg

Mass transport properties of the tetrahydronaphthalene/n-dodecane mixture measured by investigating non-equilibrium fluctuations

Croccolo, Fabrizio ; Scheffold, Frank ; Bataller, Henri

In: Comptes Rendus Mécanique, 2013, vol. 341, no. 4–5, p. 378–385

We present preliminary near-field light scattering (NFS) data concerning the analysis of the static power spectrum and of the relaxation time constant as a function of the wave vector for non-equilibrium fluctuations (NEFs). The goal of these measurements is to obtain information about the Soret and the mass diffusion coefficients of a binary mixture undergoing thermodiffusion. In particular, we...

Université de Fribourg

Thermodiffusion of the tetrahydronaphthalene and dodecane mixture under high pressure and in porous medium

Giraudet, Cédric ; Croccolo, Fabrizio ; Galliero, Guillaume ; Pijaudier-Cabot, Gilles ; Vaerenbergh, Stefan Van ; Saghir, M. Ziad ; Montel, François ; Bataller, Henri

In: Comptes Rendus Mécanique, 2013, vol. 341, no. 4-5, p. 340-347

A thermodiffusion cell is used in order to perform Soret experiments on binary mixtures at high pressure and in the presence of a porous medium. The cell is validated at atmospheric pressure with toluene/hexane and the tetrahydronaphthalene/dodecane mixtures. The mass separation follows a diffusive behaviour when the cell is filled with a porous medium. At least three times the relaxation time is...

Université de Fribourg

A light scattering study of non equilibrium fluctuations in liquid mixtures to measure the Soret and mass diffusion coefficient

Croccolo, Fabrizio ; Bataller, Henri ; Scheffold, Frank

In: Journal of Chemical Physics, 2012, vol. 137, no. 23, p. 234202

We use dynamic near field scattering to measure the dynamics of concentration non equilibrium fluctuations at the steady-state of Soret separation. The analysis reveals that above a threshold wave vector qc, the dynamics is governed by diffusion while at smaller wave vectors, gravity dominates. From the measurements, we extract both the mass diffusion and the Soret...

Université de Fribourg

Concentration dependent refractive index of a binary mixture at high pressure

Croccolo, Fabrizio ; Arnaud, Marc-Alexandre ; Bégué, Didier ; Bataller, Henri

In: Journal of Chemical Physics, 2011, vol. 135, no. 3, p. 034901

In the present work binary mixtures of varying concentrations of two miscible hydrocarbons, 1,2,3,4-tetrahydronaphtalene (THN) and n-dodecane (C12), are subjected to increasing pressure up to 50 MPa in order to investigate the dependence of the so-called concentration contrast factor (CF), i.e., (∂n/∂c)p, T, on pressure level. The refractive...