The used formula are based on the method of Chung et al (1984, 1988) referred to in ref [1] chapter 9. The formula 9-4.10 is the one being used. The formula is given in non-SI units, the following conversion constants were used to transform the formula to SI units:
[1] Bruce E. Poling, John E. Prausnitz, John P. O'Connell, "The Properties of Gases and Liquids" 5th Ed. Mc Graw Hill.
T. Skoglund, Lund, Sweden, 2004-08-31
function dynamicViscosityLowPressure extends Modelica.Icons.Function; input SI.Temperature T "Gas temperature"; input SI.Temperature Tc "Critical temperature of gas"; input SI.MolarMass M "Molar mass of gas"; input SI.MolarVolume Vc "Critical molar volume of gas"; input Real w "Acentric factor of gas"; input Modelica.Media.Interfaces.Types.DipoleMoment mu "Dipole moment of gas molecule"; input Real k = 0.0 "Special correction for highly polar substances"; output Modelica.Media.Interfaces.Types.DynamicViscosity eta "Dynamic viscosity of gas"; end dynamicViscosityLowPressure;