A quasi-universal scaling law for atomic transport in simple fluids

A semi-empirical `universal' corresponding-states relationship, for the dimensionless transport coefficients of dense fluids as functions of the reduced configurational entropy, was proposed more than twenty years ago and established by many simulations. Here it is shown analytically, by appealing to Enskog's original results for the inverse-power potentials, that the quasi-universal entropy scaling can be extended also to dilute gases. The analytic form and the possible origin for the entropy scaling for dense fluids are discussed in view of this unexpected result. On the basis of the entropy scaling we predict a minimum in the shear viscosity as a function of temperature for all soft inverse-power potentials, in quantitative agreement with the available simulations.