Phase transitions in a colloidal dispersion flowing through a cylindrical capillary

The flow of a charged-stabilized colloidal dispersion of crystalline equilibrium structure through a cylindrical capillary is investigated. The simultaneous existence of up to three differently ordered states is observed under conditions of stationary flow. The evolution of their concentric arrangement along the capillary is determined by Bragg microscopy. For sufficient low fluxes, stationary phase distributions are obtained. While the apparent viscosity is non-monotonous and non-Newtonian, the corresponding velocity profiles are found to be piecewise parabolic and are compatible to numerical calculations. Furthermore, we test the assumption of a constant yield stress determining the radia…