Molecular dynamics study on viscosities of sub/supercritical n-decane, n-undecane and n-dodecane

Viscosity is an essential property of fuels and a fundamental parameter in designing complex propulsion and power systems. In this paper, molecular dynamics (MD) simulations are conducted to compute viscosities of n-decane, n-undecane, and n-dodecane, Five force fields are compared by prediction of the viscosity. The results show that the MD predictions of the viscosity of the selected n-alkane are in good agreement with the reference data. In addition, the self-diffusion coefficient and radial distribution function of n-undecane are obtained from the MD simulations to better understand the viscosity characteristics of a sub/supercritical region at the molecular level. The Stokes-Einstein model and the Rouse model are employed to calculate the viscosity-temperature relationship of n-undecane under sub/supercritical conditions. It is found that the predicted viscosity values are significantly underestimated by the two models. This research offers reference for analyzing the thermophysical properties of N-alkanes and N-alkane-based fuels. (C) 2021 Elsevier B.V. All rights reserved.