Abstract
The shear viscosity η of the hard-sphere fluid, at volumes of 1.6 and 2 times the close-packed volume, is computed with use of nonequilibrium molecular dynamics. At high shear rate ε̇ we observe a phase transition in which the system undergoes two-dimensional ordering in the plane perpendicular to the flow, accompanied by a sharp decrease in η. For small ε̇, no evidence is found for the square-root dependence on ε̇ reported by previous investigators.