Shear flow of liquid and frozen water in a silica nanochannel

Abstract

Using molecular dynamics simulation, we analyze the processes occurring in an amorphous ice layer separating two silica blocks which slide over each other and compare it to the case of liquid water at higher temperatures. The shear velocity profiles in the ice and water are surprisingly similar, while the viscosity of ice is substantially larger than that of liquid water. The flow in amorphous ice is non-Newtonian—the shear viscosity increases for smaller shear rates—while the flow in liquid water is Newtonian. Snapshots of the shear process in ice demonstrate how—at low temperatures—the initially almost elastic response of the ice transforms at higher shears to the break-up of hydrogen bonds between \(\textrm{H}_{2}\textrm{O}\) molecules and a molecular mixing in the amorphous ice.