Deformation of a single rising bubble in non-Newtonian liquid

A shape of a bubble in PolyAcrylAmide (PAA) water solution, which is a typical viscoelastic model fluid, is examined with visualization experiment. In order to study the fundamental aspect of the bubble shape attention was given for a single bubble rising upward against the gravity. Range of size of bubble in the present investigation covers from 0.32 mm up to 12.1 mm, small size to intermediate size. To characterize a bubble in the viscoelastic fluid, Newtonian fluid (glycerine water solution), whose shear viscosity is the same as the viscoelastic one, is also used for the sake of comparison. From results of this study, it was observed that the shape of a small bubble can be kept spherical for both viscoelastic and Newtonian fluids. However, when the size of bubble is increased, the shape is largely deformed with a spike in the tale of rising bubble in the case of the viscoelastic fluid.