It is shown that the shear-viscosity formulas derived by the modified moment method can adequately account for the shear rate and frequency dependence of the viscoelastic properties of a two-dimensional fluid computed by Evans et al. by a nonequilibrium molecular-dynamics method. The nonlinear shear viscosity computed from these formulas are positive everywhere for all values of shear rate and frequency.

• Received 18 November 1986

DOI:https://doi.org/10.1103/PhysRevA.35.4850