Bubble Formation at Orifice in Viscoelastic Liquids

To evaluate the effect of viscoelasticity on bubble formation, four rheological parameters of viscoelastic liquids were defined and measured by a rheometer. The effects of operating conditions and concentration of polyacrylamide aqueous solutions (PAA) as viscoelastic liquids on bubble volume and the growth curve were experimentally measured. A high-speed video camera showed that the shapes of a bubble growing in viscoelastic liquids are not spherical. In this study, a nonspherical bubble formation model was proposed to theoretically estimate the volume, shape and growth curve of bubbles formed from an orifice submerged in viscoelastic liquids which are assumed to follow Maxwell's viscoelastic model. This experimental results in relatively low concentrations of PAA, as well as previous researchers' results, agreed relatively well with the calculated ones by this model.