The temperature and depth dependence of the shear viscosity (η) of the quasi-liquid layer (QLL) of water on ice-I<sub>h</sub> crystals was determined using simulations of the TIP4P/Ice model. The crystals display either the basal {0001} or prismatic {10-10} facets, and we find that the QLL viscosity depends on the presented facet, the distance from the solid / liquid interface, and the undercooling temperature. Structural order parameters provide two distinct estimates of the QLL widths, which are found to range from 6.0-7.8 Å, and depend on facet and undercooling temperature. Above 260 K, the viscosity of the vapor-adjacent water layer is significantly less viscous than the solid-adjacent layer, and is also lower than the viscosity of liquid water.<br/><br/>Simulations of solid / liquid friction at ice / water interfaces also suggest that the surface density of solid to liquid hydrogen bonds directly correlates with interfacial friction. When the basal {0001}, prismatic {10-10}, pyramidal {20-21}, and secondary prism {11-20} facets of ice are were drawn through liquid water, the interface is in negative slip conditions. Careful treatment of friction in this regime will be discussed, and the friction of these interfaces is found to be invariant to the shear rate and direction of shear relative to the surface features, but highly dependent on the density of solid to liquid hydrogen bonds, which does depend strongly on surface features of the four facets.

Why is ice slippery? Simulations of solid-liquid friction and the shear viscosity of the quasi-liquid layer on ice

2019 Fall National Meeting

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