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

  • Croccolo, Fabrizio Department of Physics, University of Fribourg, Switzerland
  • Scheffold, Frank Department of Physics, University of Fribourg, Switzerland
  • Bataller, Henri Laboratoire des Fluides Complexes et leurs Réservoirs – UMR 5150, Université de Pau et des Pays de lʼAdour, France
    19.02.2013
Published in:
  • Comptes Rendus Mécanique. - 2013, vol. 341, no. 4–5, p. 378–385
Soret coefficient
mass diffusion coefficient
non equilibrium fluctuations
differential dynamic analysis
near field scattering
English 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 show how the interaction between NEFs and the gravity force gives rise to a critical wavelength that provides additional information about the Soret coefficient. We suggest that a quantitative analysis can be performed by means of this non-invasive optical technique. In our setup, the sample is monitored parallel to the imposed temperature gradient, thus being insensitive to the refractive index profile along the vertical axis, while at the same time we are able to detect the light scattered by the refractive index fluctuations in horizontal planes. We select a shadowgraph layout for the NFS setup due to the extremely small wave vectors we aim to analyze. From a double-frame differential analysis of the acquired images, we obtain both the static power spectrum and the dynamics of NEFs. As a proof-of-principle experiment, we present Soret and diffusion coefficient data on a liquid mixture of tetrahydronaphthalene/n-dodecane.
Faculty
Faculté des sciences et de médecine
Department
Département de Physique
Language
  • English
Classification
Physics
License
License undefined
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Persistent URL
https://folia.unifr.ch/unifr/documents/303019
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