Rheology of cholesteric blue phases.

Cholesteric blue phases are a spectacular example of disclination line networks. Here we numerically investigate their response to an imposed Poiseuille flow. We show that shear forces bend and twist and can unzip the disclination lines. Under gentle forcing the network opposes the flow and the apparent viscosity is large. With increased forcing we find strong shear thinning corresponding to the disruption of the network. As the viscosity starts to drop, the imposed flow sets the network into motion. Disclinations break up and re-form with their neighbors along the flow.