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J Chem Phys. 2015 May 07;142(17):174501. doi: 10.1063/1.4919296.

Thermodynamic scaling of the shear viscosity of Mie n-6 fluids and their binary mixtures.

The Journal of chemical physics

Stephanie Delage-Santacreu, Guillaume Galliero, Hai Hoang, Jean-Patrick Bazile, Christian Boned, Josefa Fernandez

Affiliations

  1. Laboratoire de Mathématiques et leurs Applications (UMR-5142 with CNRS), Université de Pau et des Pays de l'Adour, BP 1155, F-64013 PAU Cedex, France.
  2. Laboratoire des Fluides Complexes et leurs Reservoirs (UMR-5150 with CNRS and TOTAL), Université de Pau et des Pays de l'Adour, BP 1155, F-64013 PAU Cedex, France.
  3. Laboratorio de Propiedades Termofisicas, Universidade Santiago de Compostela, Campus Vida, E-15782 Santiago de Compostela, Spain.

PMID: 25956107 DOI: 10.1063/1.4919296

Abstract

In this work, we have evaluated the applicability of the so-called thermodynamic scaling and the isomorph frame to describe the shear viscosity of Mie n-6 fluids of varying repulsive exponents (n = 8, 12, 18, 24, and 36). Furthermore, the effectiveness of the thermodynamic scaling to deal with binary mixtures of Mie n-6 fluids has been explored as well. To generate the viscosity database of these fluids, extensive non-equilibrium molecular dynamics simulations have been performed for various thermodynamic conditions. Then, a systematic approach has been used to determine the gamma exponent value (γ) characteristic of the thermodynamic scaling approach for each system. In addition, the applicability of the isomorph theory with a density dependent gamma has been confirmed in pure fluids. In both pure fluids and mixtures, it has been found that the thermodynamic scaling with a constant gamma is sufficient to correlate the viscosity data on a large range of thermodynamic conditions covering liquid and supercritical states as long as the density is not too high. Interestingly, it has been obtained that, in pure fluids, the value of γ is directly proportional to the repulsive exponent of the Mie potential. Finally, it has been found that the value of γ in mixtures can be deduced from those of the pure component using a simple logarithmic mixing rule.

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