INVESTIGATION OF THE HOMOGENEOUS-SHEAR NONEQUILIBRIUM-MOLECULAR-DYNAMICS METHOD

The homogeneous-shear (HS) technique has been used extensively to study shear flow, but it uses artificial methods to remove the viscous heat generated. In reality the viscous heat is removed from the system by conduction out through the boundaries. This inevitably leads to characteristic gradients in temperature, density, and shear rate. While at low shear rates these effects may be neglected, and the use of HS justified, at high shear rates they certainly cannot, and doubts remain as to the validity of HS in this regime. In this study we make careful comparisons between HS and a more-realistic sliding-boundary method. HS gives very similar results when conditions corresponding to different regions within the sliding system are used. The use of HS simulations at shear rates where energy is generated at a rate faster than can be realistically removed by any natural process is called into question.