Shear viscosity via global control of spatiotemporal chaos in two-dimensional isoenergetic dense fluids

Abstract

We control the chaotic large-scale spatiotemporal fluctuations inherent in large-scale two-dimensional nonequilibrium flows by using global ergostats. We use isoenergetic nonequilibrium molecular dynamics to characterize the size dependence of both the shear viscosity and the largest Lyapunov exponent for two-dimensional globally controlled dense periodic fluids. Though uncontrolled fluctuations in such flows have often been thought to lead to divergent transport coefficients in two dimensions, our numerical evidence shows instead that the large-system ‘‘thermodynamic limit’’ can be extended to a convergent homogeneous ‘‘hydrodynamic limit’’ away from equilibrium, with finite transport coefficients, even in two dimensions.