Effect of confinement on the rheology of a yield-stress fluid

摘要: Abstract We have studied the flow of Carbopol, a polymer microgel, confined to approximately square microchannels with widths ranging from 451 µm down 54 µm. Velocity profiles in midplane channels were measured using particle image velocimetry. Carbopol is yield-stress fluid, and velocity larger agreed well simulations based on its bulk-scale rheology. In 150 µm or smaller width, however, could not be fitted by model finite yield stress, but instead well-described power-law zero stress. explain vanishing stress terms confinement structural elements Carbopol.