Reference Correlation for the Viscosity of Helium

We present a new wide-ranging correlation for the viscosity of normal helium (He I) based on critically evaluated experimental data as well as high-accuracy ab initio calculations. The correlation is designed to be used with densities from a high-accuracy Helmholtz equation of state, covering temperatures from 2.1768 K to 1500 K and pressures up to 2000 MPa. The estimated uncertainty at the 95 % confidence level depends on temperature and pressure, spanning from 0.002 % in the dilute gas limit (298.15 K, 0 MPa) to 10 % for the liquid phase at pressures from saturation up to 8 MPa. Finally, we provide comprehensive comparisons with experimental data and Python code to facilitate easy implementation.

The online version contains supplementary material available at https://doi.org/10.1007/s10765-026-03816-5.