BUBBLE FORMATION AT A SUBMERGED ORIFICE IN NON-NEWTONIAN AND HIGHLY VISCOUS NEWTONIAN LIQUIDS

Bubble formation at a submerged orifice was studied experimentally for non-Newtionian liquids (aqueous CMC solutions) and highly viscous Newtonian liquids (aqueous glycerol solutions). The bubble volumes formed in both non-Newtonian and highly viscous Newtonian liquids are large compared to those formed in relatively low-viscosity Newtonian liquids. The formation regime of the constant-pressure condition, usually found for low-viscosity Newtonian liquids as reported by Tadaki et al., was not observed. Using an extended two-stage bubble-formation model, the bubble volumes formed at a submerged orifice in non-Newtonian and highly viscous Newtonian liquids are considered. The predicted bubble volumes compare satisfactorily with the experimental data over a wide range of parameters of power law liquid (mn, 0.95>n>0.57) and viscosities of Newtonian liquids (5.05 PaDOTs>μl>0.439 Pa&middots) including the results of the present work and that of Tsuge et al.