Shear Viscosity of Model Mixtures by Nonequilibrium Molecular Dynamics. IV. Effect of Molecular Shape

We present new results for thermodynamic properties and viscosities of pure dumbbell fluids, spherical/dumbbell mixtures, and dumbbell/dumbbell mixtures. It is evident that the interaction between dumbbell molecules is less attractive than that between spherical molecules which leads to lower viscosities. The shear viscosities and the LJ energies of both spherical Ar/dumbbell Kr (case B) and dumbbell Ar/dumbbell Kr (case C) are described quite well by the liquid mixture expression. The ideality in case C is much better than in case B which is consistent with the idea that dumbbell/dumbbell mixtures are likely to be more ideal than spherical/dumbbell mixtures. But the mixture pressures of the spherical/dumbbell mixture (case B) are described accurately by the ideal liquid mixture expression while those of the dumbbell/dumbbell mixture (case C) are not, which is not consistent with the better ideality of case C in the shear viscosity and the LJ energy than case B.