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Poster De Conférence Année : 2014

THERMODYNAMIC SCALING OF VISCOSITY APPLIED TO MIXTURES: MODEL AND REAL FLUIDS

Résumé

Nearly forty years ago, Ashurst and Hoover [1] have shown that the shear reduced residual viscosity of dense fluids composed of soft spheres can be described by a function of rg/T only, where T is the temperature and r the density. g is a parameter which is a measure of the repulsion steepness of the interaction potential between particles. More recently, it has been found that this so-called "thermodynamic scaling" holds for a large class of real liquids [2] and is applicable even for moderately dense fluids [3]. To further extent this approach to larger class of fluid systems including mixtures, we have first performed numerous molecular dynamics simulations on model fluids in which the interaction were described by a Mie n-6 potential where n is the repulsion exponent (varying between 8 and 36). To determine unambiguously the optimal g, we have defined a general strategy based on a modified Avramov's relation between the reduced residual viscosity and rg/T. Using that scheme, it has been found that the thermodynamic scaling holds very well for such model fluids and that the optimal g is simply related to the repulsion exponent n of the Mie potential, as expected. Then, we have performed simulations on mixtures of these model fluids. First, it has been found that the thermodynamic scaling of the viscosity is well respected in binary mixture of Mie fluids. Second, it has been observed that a simple logarithmic mixing rule yields an excellent estimate of the g value in mixtures. Finally, it has been noticed that these findings hold very well even when dealing with real (alcohols, alkanes ...) fluid mixtures. [1] Ashurst, W. T.; Hoover, W. G., Physical Review A 1975, 11, 658-678. [2] Roland, M.; Hensel-Bielkowka, S.; Paluch, M.; Casalini, R., Rep. Prog. Phys. 2005, 68, 1405-1478. [3] Galliero, G.; Boned, C.; Fernandez, J., Journal of Chemical Physics 2011, 134, 064505.
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hal-00996307 , version 1 (25-05-2021)

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  • HAL Id : hal-00996307 , version 1

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Guillaume Galliero, Stephanie Delage Santacreu, Jean-Patrick Bazile, J. Fernandez, Christian Boned. THERMODYNAMIC SCALING OF VISCOSITY APPLIED TO MIXTURES: MODEL AND REAL FLUIDS. ECTP 2014 - European Conference on Thermophysical Properties (http://ectp2014.fc.up.pt/), Aug 2014, porto, Portugal. pp.00, 2014. ⟨hal-00996307⟩
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