Some physical consequences of large shear rates on simple liquids

Abstract

The structural and dynamical changes that take place in simple liquids and glasses during extreme shear thinning are investigated by nonequilibrium molecular dynamics (NEMD). Simulations performed on the Lennard-Jones liquid at states close to the triple point reveal long range order accompanying extreme shear thinning which is characterized by linear lines of molecules spontaneously forming along the shear flow lines. These ‘‘strings’’ of molecules pack into a triangular lattice. The density of strings increases with shear rate, as does the difference in density in various directions with respect to the flow field. Local structural asymmetry with lifetimes comparable to the simulation are observed at the highest shear rates considered, leading eventually to structural disorder via dislocations in the triangular lattice.