Above the critical stress for slip, the procedures normally used to analyze the results of
capillary flow data give anomalous results. In particular, the Bagley plots are curved, even
when a variation of viscosity with pressure is not anticipated, and the Mooney technique
used to calculate the slip velocity gives results that indicate that the slip velocity depends on
the L/D ratio. It is proposed that these phenomena arise from the dependence of the slip
velocity on the wall normal stress, which implies a dependence on pressure. Based on this …