Flow Properties of Ultra-Fine Bubble Mixtures Passing through Micro-Apertures

Abstract

The flow properties of fine bubble mixture flows are investigated and reported. Few previous studies have focused on ultra-fine bubble (UFB) mixtures, which contain sub-micrometer sized bubbles. In this study, UFB mixtures of water and glycerol solution are passed through micro-sized slits and capillaries, and the resultant pressure drops are evaluated in comparison with those for water and aqueous glycerol alone. The experimentally measured pressure drop for slits (≤51 μm) and capillaries (≤81 μm) is less for UFB mixtures than for water and aqueous glycerol alone. This phenomenon is considered in terms of interface behavior and attributed to the electric interaction between an electric double layer and the UFBs. Furthermore, numerical observation for slip wall conditions is conducted, and the results for UFB mixtures agree with the predicted values for slip wall conditions.