Ice Crystallization in Shear Flows

Ice formation under a shear is a common phenomenon in nature. Unfortunately, the role of shear rates in affecting the ice growth rate and the underlying microscopic mechanisms are not well understood. In this work, we investigate the ice growth rate in shear flows through molecular dynamics simulations. Under sufficient supercooling, it is found that the growth rate varies nonlinearly as the shear rate is increased and assumes a maximum at an intermediate shear rate. This is caused by two distinct effects of the shear on the ice crystallization. On the one hand, a shear can help break the hydrogen bond network (HBN) in water and free some water molecules to reorganize at the water-ice interface to form ice. On the other hand, the shear can also disrupt the water-ice hydrogen bonds and thus hinder the growth of ice. At low shear rates, the former effect is important, while the latter influence becomes dominant at high shear rates. The competition of these two effects leads to the nonlinear dependence. Close to the melting point, however, the thermal effect weakens the role of the shear rate in promoting ice growth, and the growth rate shows monotonous decrease with increasing shear rate.