The Motion and Associated Mass Transfer Characteristics of Gas Bubbles in Viscoelastic Liquids

Citation

Zana, Erdinc (1975) The Motion and Associated Mass Transfer Characteristics of Gas Bubbles in Viscoelastic Liquids. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/exg0-az53. https://resolver.caltech.edu/CaltechTHESIS:05172023-213904882

Abstract

The motion and associated mass transfer characteristics of gas bubbles in viscoelastic liquids is investigated in the limits of Pe << 1 and Pe >> 1. Full numerical and approximate analytical solutions are obtained for Pe << 1 case in order to investigate the roles of shear viscosity, relaxation and retardation times, surface tension and the Henry's law constant on the dissolution rate. It is shown that the collapse characteristics and the behavior of internal pressure in the viscoelastic liquid differ considerably from the case of a purely Newtonian liquid, particularly during the early and late stages of the dissolution process.

The Pe >> 1 case is studied experimentally. The mass transfer rates from gas bubbles rising in viscoelastic liquids are measured and the data are shown to correlate very well with Weissenberg number. It is also shown that mass transfer rate from a gas bubble is greatly enhanced by viscoelasticity over its value for a Newtonian liquid with the same shear viscosity. The terminal rise velocities of bubbles in viscoelastic liquids are also measured. The well known discontinuity in the bubble rise velocity is fully investigated. It is shown that the magnitude of the velocity discontinuity may be accounted for by considering shear dependent viscosity and viscoelasticity. A tentative explanation for the abruptness of the velocity transition is presented.

Finally, the streamline flow visualization experiments for viscoelastic liquids past a solid sphere are presented. The results show that the streamlines are shifted in the upstream direction and the amount of shift increases with viscoelasticity.

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