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 mixtur es. It is evident that the interaction between dumbbell molecules is less a ttractive than that between spherical molecules which leads to lower viscos ities. The shear viscosities and the LJ energies of both spherical Ar/dumbb ell Kr (case B) and dumbbell Ar/dumbbell Kr (case C) are described quite we ll 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 mix tures 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 dumbb ell/dumbbell mixture (case C) are not, which is not consistent with the bet ter ideality of case C in the shear viscosity and the LJ energy than case B .