Abstract
Coating flows of polymeric liquids in a pipe was studied. A bubble of air was injected into a pipe filled with a test fluid to form hydrodynamic coating on a pipe wall. The film thickness was evaluated by hydrodynamic fractional coverage m. The fractional coverage was characterized using the capillary number Ca and the Weissenberg number We. The film was thinner than that of the Newtonian case at the same Ca when the viscous property was dominant, i.e. We was small. Shear-thinning viscosity made the film thin. On the other hand, the film became thicker than the corresponding Newtonian results at large We because of normal stress effect.
