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Keywords:

  • computer simulations (MC and MD);
  • thermodynamics/statistical;
  • rheology;
  • liquids;
  • nonequilibrium thermodynamics

Abstract

Nonequilibrium molecular dynamics simulation data for a 12-6 Lennard-Jones fluid are obtained over a wide range of temperatures, densities and strain-rates. The data, which cover 660 different state points, are used to deduce the nonequilibrium contributions to the energy and pressure of the fluid under steady-state conditions. These contributions are analysed and used in conjunction with an equilibrium equation of state to obtain an accurate nonequilibrium steady-state equation of state for the 12-6 Lennard-Jones fluid. Comparison with simulation data indicates that the nonequilibrium contributions can be obtained with a similar accuracy to the equilibrium contributions. Relationships for the shear viscosity as functions of density and pressure are obtained, which adequately reproduce the shear viscosity simulation data. The isochoric shear viscosity as a function of pressure is shown to be independent of strain-rate at sufficiently high strain-rates. © 2010 American Institute of Chemical Engineers AIChE J, 2011