Juraivan Ratanapisit and James F. Ely

pp. 847 - 857

Abstract

In this paper, we represent the viscosity of hard chain fluids. This study was initiated with an investigation of the equilibrium molecular dynamic simulations of pure hard-sphere molecules. The natural
extension of that work was to hard chain fluids. The hard chain model is one in which each molecule is
represented as a chain of freely jointed hard spheres that interact on a site-site basis. The major use of the
results from this study lie in the future development of a transport perturbation theory in which the hard
chain serves as the reference. Our results show agreement to within the combined uncertainties with the
previous studies. Comparisons have also been made to a modified Enskog theory. Results show the failure of
the Enskog theory to predict the high density viscosity and that the theory fails more rapidly with density
as the chain length increases. We attribute this to a failure of the molecular chaos assumption used in the
Enskog theory. Further comparisons are made to real fluids using the SAFT-MET and TRAPP approaches. As expected, the hard sphere model is not appropriate to estimate properties of real fluids. However, the
hard sphere model provides the good starting point to serve as the reference basis to study chain molecule
systems.