Non-Newtonian flow effects in supercooled water

Abstract

The viscosity of supercooled water has been a subject of intense study, in particular with respect to its temperature dependence. Much less is known, however, about the influence of dynamical effects on the viscosity in its supercooled state. Here we address this issue for the first time, using molecular dynamics simulations to investigate the shear-rate dependence of the viscosity of supercooled water as described by the TIP4P/Ice model. We show the existence of a distinct crossover from Newtonian to non-Newtonian behavior characterized by a power-law shear-thinning regime. The viscosity reduction is due to the decrease in the connectivity of the hydrogen-bond network. Moreover, the shear thinning intensifies as the degree of supercooling increases, whereas the crossover flow rate is approximately inversely proportional to the Newtonian viscosity. These results stimulate further investigation into possible fundamental relations between these nonequilibrium effects and the quasistatic Newtonian viscosity behavior of supercooled water.

Effect of Sodium Chloride on Internal Quasi-Liquid Layers in Ice Ih

“…Figure a displays its behavior for the three considered salinities as a function of the shear strain, defined as γ ≡ Δ y / L z , with Δ y the relative displacement of the grains in the y -direction and L z the size of the bicrystal in the z direction. The stress–strain curves are qualitatively the same for all cases and resemble the typical behavior of viscoelastic systems. − The initial response is elastic in nature, with the shear stress increasing linearly with the strain. In this regime the displacement of the upper grain is small, giving rise to elastic shear deformations of the crystal grains but without evoking any sliding at the GB region.…”

Does supercooled water retain its universal nucleation behavior under shear at high pressure?

“…As the shear rate increases, there is a crossover from the Newtonian regime to the shear thinning regime. According to Ribeiro et al , 65 this shear thinning results from a decreased connectivity of hydrogen bonding networks. The viscosity at different shear rates is described using the Carreau model 65 defined aswhere η ∞ is the viscosity at the shear rate , η N is the Newtonian viscosity, 0 is the crossover shear rate and n is the shear-thinning exponent which ranges between 0 and 1.…”

Grain-Boundary Sliding in Ice Ih: Tribology and Rheology at the Nanoscale

“…For both temperatures, the stress response is manifestly nonmonotonic, resembling the typical viscoelastic behavior observed for a number of polymeric and/or glassy systems subjected to shear deformation, 62−70 including bulk supercooled liquid water. 71 The initial response is elastic in nature, with σ yz increasing linearly as a function of the strain γ and the slope being independent of the sliding velocity (see insets in Figure 3a,b). In the elastic regime, the displacement of the top layer is small, ≲3 Å, giving rise to elastic shear deformations of the crystal grains but without sliding activity at the interface.…”