Molecular dynamics simulations of the rheological properties of simple fluids

We review some of the principal results obtained from non-equilibrium molecular dynamics simulations of Couette flow in fluids. The simulations show that even simple fluids exhibit a wide variety of non-Newtonian behaviour (e.g., viscoelasticity, shear thinning and dilatancy, normal stress differences and non-local momentum transport). The asymptotic dispersion relations for each of these effects is consistent with the non-analytic functional forms predicted using “long-time-tail” theories. However in each case, the magnitude of the observed effect is much larger than theoretical predictions. We show that non-linear irreversible thermodynamics successfully relates a number of these non-Newtonian effects observed, very far from equilibrium, outside the regime of local thermodynamic equilibrium.