Vol.:(0123456789)
International Journal of Thermophysics (2025) 46:133
https://doi.org/10.1007/s10765-025-03603-8
Reference Correlation oftheViscosity ofArgon
SoaG.Sotiriadou
1
· KonstantinosD.Antoniadis
2
· MarcJ.Assael
1
·
MarciaL.Huber
3
Received: 4 June 2025 / Accepted: 20 June 2025
This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection
may apply 2025
Abstract
This paper presents a new wide-ranging reference correlation for the viscosity of
argon, incorporating recent ab initio dilute-gas calculations and critically evalu-
ated experimental data. The correlation is designed to be used with a high-accuracy
Helmholtz equation of state that extends from the triple point (83.8058K) to 700K,
and at pressures up to 1000MPa. The estimated uncertainty of the correlation based
on comparisons with the best experimental data indicate that the uncertainty for the
gas at pressures from zero to 0.1 MPa for temperatures from 202 K to 394 K is
0.076% (at k = 2), the uncertainty of the best experimental data, offering a signifi-
cant improvement over the current reference equation that has an uncertainty in this
region of 0.5%. A zero-density correlation based on ab-initio values is incorporated
that is valid over a temperature range between 84K and 10 000K and has an uncer-
tainty of 0.12% (at the 95% confidence level). The estimated uncertainty for moder-
ate pressures from 1MPa to 100MPa is 1% for temperatures from roughly 195K
to 300K, rising to 2% at 175K. For the high-pressure region, the estimated uncer-
tainty of the correlation is about 2% for temperatures between 175K and 308K at
pressures from 100MPa to 606MPa. For temperatures from 308K to 700K at pres-
sures to 5.2 GPa, the equation has an estimated uncertainty of 10%. The estimated
uncertainty in the liquid phase at pressures up to 34 MPa is 3%. The correlation
behaves in a physically reasonable manner over the full range of applicability of the
EOS, although uncertainties may be higher in regions where data were not available
for full validation.
Keyword Argon· Transport properties· Viscosity
* Marcia L. Huber
marcia.huber@nist.gov
1
Laboratory ofThermophysical Properties andEnvironmental Processes, Chemical Engineering
Department, Aristotle University, 54636Thessaloniki, Greece
2
Chemical Engineering Department, University ofWestern Macedonia, 50100Kozani, Greece
3
Applied Chemicals andMaterials Division, National Institute ofStandards andTechnology, 325
Broadway, Boulder, CO80305, USA
