Microscopic interpretation of viscosity for simple fluids

Abstract

The main objective of this study is to provide a novel microscopic interpretation of the viscosity of simple fluids on the basis of the law of energy conservation applied to simple shear or Couette flow. Ultimately reflecting the balance between stored and dissipated energy. This balance then leads to an expression for the viscosity: η = G0τ , with G0 the instantaneous elastic modulus and τ the relaxation time. By means of linear oscillatory rheology we measure the viscosity of a liquid and its relaxation time, then obtain an estimate of G0. The value of η is then confirmed by steady-state rheology measurements.