Dilute gas viscosity of n-alkanes represented by rigid Lennard-Jones chains
File(s)
Author(s)
Castro-Palacio, JC
Hellmann, R
Vesovic, V
Type
Journal Article
Abstract
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 , 0.333 , 0.40 , 0.60 and 0.80 , where is the Lennard-Jones
length scaling parameter. The results were used to determine the shear viscosity of n-alkanes in the zerodensity
limit by representing an n-alkane molecule as a rigid linear chain consisting of c − 1 spherical
segments, where c is the number of carbon atoms. We show that for a given n-alkane molecule, the
scaling parameters ε and σ 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.
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 , 0.333 , 0.40 , 0.60 and 0.80 , where is the Lennard-Jones
length scaling parameter. The results were used to determine the shear viscosity of n-alkanes in the zerodensity
limit by representing an n-alkane molecule as a rigid linear chain consisting of c − 1 spherical
segments, where c is the number of carbon atoms. We show that for a given n-alkane molecule, the
scaling parameters ε and σ 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.
Date Issued
2016-09-01
Date Acceptance
2016-08-04
Citation
Molecular Physics, 2016, 114 (21), pp.3171-3182
ISSN
0026-8976
Publisher
Taylor & Francis
Start Page
3171
End Page
3182
Journal / Book Title
Molecular Physics
Volume
114
Issue
21
Copyright Statement
© 2016 Informa UK Limited, trading as Taylor & Francis Group. This is an Accepted Manuscript of an article published by Taylor & Francis in Molecular Physics on 1 Sep 2016, available online: http://dx.doi.org/10.1080/00268976.2016.1222456
Sponsor
Imperial College Trust
Grant Number
N/A
Subjects
Science & Technology
Physical Sciences
Chemistry, Physical
Physics, Atomic, Molecular & Chemical
Chemistry
Physics
n-Alkanes
viscosity
dilute gas
Lennard-Jones chains
POTENTIAL-ENERGY SURFACE
EQUATION-OF-STATE
TRANSPORT-PROPERTIES
REAL FLUIDS
THERMOPHYSICAL PROPERTIES
THERMAL-CONDUCTIVITY
MOLECULAR SIMULATION
SHEAR VISCOSITY
MIE POTENTIALS
BULK VISCOSITY
0202 Atomic, Molecular, Nuclear, Particle And Plasma Physics
0306 Physical Chemistry (Incl. Structural)
0307 Theoretical And Computational Chemistry
Chemical Physics
Publication Status
Published