SHEAR VISCOSITY OF POLAR LIQUID-MIXTURES VIA NONEQUILIBRIUM MOLECULAR-DYNAMICS - WATER, METHANOL, AND ACETONE

Non-equilibrium molecular dynamics (NEMD) with isobaric and isokinetic controls were used to simulate the shear viscosity for binary mixture s of water, methanol and acetone, and for ternary mixtures. In all, 22 different liquid composition points were simulated at 298.15 K and 0. 1 MPa. A new set of acetone potential parameters was developed, while slight variants to existing water and methanol models were used. Long range Coulombic interactions were computed with the Ewald sum adapted to Lees-Edwards boundary conditions as formulated in Wheeler, D. R., F uller, N. G., and Rowley, R. L., 1997, Molec. Phys., 92, 55. The attra ctive (dispersive) part of the Lennard-Jones (LJ) interactions also wa s handled by a lattice sum. A hybrid mixing rule was used for the LJ c ross interactions. Viscosities extrapolated to zero shear compared wel l with experimental results, having a mean absolute error of 14% and n o errors greater than 30%. Although the simulations successfully predi cted viscosity maxima for mixtures high in water content, the peak hei ghts tended ro be too low, probably due to the limitations of the wate r model. The results suggest that NEMD may be a viable means of estima ting viscosities for polar liquid mixtures with an unrestricted number of components.