Influence of the repulsive coefficient n and approximate corresponding states in Mie n-6 and exponential n-6 fluids.

Guillaume Galliero (1) , Christian Boned (2) , Antoine Baylaucq (2) , François Montel (3)

1 LETEM - Laboratoire d'Etudes des Transferts d'Energie et de Matière
2 TEFC - Thermodynamique et Energétique des fluides complexes
3 CSTJF - Centre scientifique et Technique Jean Feger

Nonequilibrium molecular dynamics (NEMD) simulations of the Mie alpha-6 and the exponential alpha-6 (exp alpha-6) fluids have been carried out for 42 thermodynamic states. Various repulsive coefficients have been studied, alpha ranging from 9 to 14 for the Mie alpha-6 potentials and from 11 to 16 for the exp alpha-6 ones, which corresponds to a total of 603 points of simulation of stable phases. The simulations have shown that, for a given set of reduced temperature and density (using an appropriate scaling procedure), the reduced pressure varies linearly with sqrt(alpha-6) for the Mie alpha-6 potentials and with sqrt(alpha -7) for the exp alpha-6 potentials. Concerning the viscosity, it is shown that, for both potential families, the variation is linear with alpha. Thus, an approximate corresponding states scheme exists on pressure and on viscosity for fluids modelled by both potentials families, but only for each property separately. In addition, it appears that, approximate corresponding states exist between fluids modelled by a Mie alpha-6 potential and an exp (alpha+2)-6 one for pressure, and between fluids modelled by a Mie alpha-6 potential and an exp (alpha+2.5)-6 one for viscosity. So, despite obvious similarities, the influence of the shape of the potential on pressure and on viscosity is not strictly the same. Hence, a complete perfect corresponding states scheme (including both the pressure and the viscosity) seems hardly feasible between fluids modelled by the Mie alpha-6 and the exp alpha-6 potential families.

Domaines: Chimie-Physique [physics.chem-ph]; Milieux fluides et réactifs; Chimie théorique et/ou physique

Guillaume Galliero, Christian Boned, Antoine Baylaucq, François Montel. Influence of the repulsive coefficient n and approximate corresponding states in Mie n-6 and exponential n-6 fluids.. Chemical Physics, 2007, 333 (2-3), pp.219-228. ⟨10.1016/j.chemphys.2007.02.002⟩. ⟨hal-00322173⟩