Fig. 2

Collision diameter σ_col (open circles) and molecular diameter for a hard-sphere gas d_h (filled red squares) vary as a function of the gas temperature, and they are normalised by the molecular diameter in MD σ_Ar=3.405×10⁻¹⁰ m. By using Eq. (6) the prediction based on the viscosity of Lennard-Jones (LJ) fluids (filled green diamonds) [36, 37] is also included for comparison. It can be seen that quasi-linear (i.e. MD simulations) or roughly linear (i.e. the hard-sphere gas) relationship exists in explored gas temperatures