Finite temperature and athermal simulations are used to determine the viscosity μ and diffusivity D for systems undergoing shear flow at shear rate γ and temperature T. Athermal simulations show that $\mu \sim {\gamma }^{-1}$ and $D\sim \gamma$ due to strain-activated relaxations, leading to an athermal Stokes-Einstein-like relation $\mu {D=C}_{\mathrm{ASE}}.$ Finite temperature simulations show that at high T the Stokes-Einstein relation $\mu {D=C}_{\mathrm{SE}}T$ is followed, and as T decreases $\mu D$ diverges in the Newtonian limit, but $\mu D$ reaches the constant value $C_{\mathrm{ASE}}$ for finite γ. These different behaviors of $\mu D$ suggest that particle dynamics are fundamentally different as jamming is approached by reducing a driving force as opposed to cooling, and that dynamic heterogeneities play a different role in shear-induced dynamics.

• Received 30 May 2002

DOI:https://doi.org/10.1103/PhysRevE.66.051202