Shear viscosity of linear alkanes through molecular simulations: quantitative tests for n-decane and n-hexadecane

Abstract

Atomistic molecular dynamics simulations were carried out at equilibrium to calculate the shear viscosity of n-decane and n-hexadecane under ambient and high temperature–high pressure conditions. Two force fields, one using a computationally efficient united-atom (TrAPPE-UA) approach and another an all-atom (AA) approach (Tobias, Tu and Klein), were employed. Quantitative agreement with experimental data is obtained with the AA force field, whereas the UA model predicts the viscosity within 20–30% of the experiment. The intra- and inter-molecular structure of the fluid obtained from these two models is similar, pointing to the role of differences in their dynamical characteristics to the observed difference in the calculated viscosities.

Keywords:

• molecular dynamics simulation
• shear viscosity
• Tobias–Tu–Klein all-atom force field
• TrAPPE united-atom force field