Dilute gas viscosity of n-alkanes represented by rigid Lennard-Jones chains

作者：Castro Palacio Juan Carlos; Hellmann Robert; Vesovic Velisa

来源：Molecular Physics, 2016, 114(21): 3171-3182.

DOI：10.1080/00268976.2016.1222456

• n-Alkanes
• viscosity
• dilute gas
• Lennard-Jones chains

The shear viscosity in the dilute gas limit has been calculated by means of the classical trajectory method for a gas consisting of chain-like molecules. The molecules were modelled as rigid chains made up of spherical segments that interact through a combination of site-site Lennard-Jones 12-6 potentials. Results are reported for chains consisting of 2, 3, 4, 6, 8, 12 and 16 segments in the reduced temperature range of 0.3-50 for site-site separations of 0.25 sigma, 0.333 sigma, 0.40 sigma, 0.60 sigma and 0.80 sigma, where s is the Lennard-Jones length scaling parameter. The results were used to determine the shear viscosity of n-alkanes in the zero-density limit by representing an n-alkane molecule as a rigid linear chain consisting of n(c) - 1 spherical segments, where n(c) is the number of carbon atoms. We show that for a given n-alkane molecule, the scaling parameters epsilon and sigma are not unique and not transferable from one molecule to another. The commonly used site-site Lennard-Jones 12-6 potential in combination with a rigid-chain molecular representation can only accurately mimic the viscosity if the scaling parameters are fitted. If the scaling parameters are estimated from the scaling parameters of other n-alkanes, the predicted viscosity values have an unacceptably high uncertainty.

• 出版日期2016