Flow Properties of Microbubble/Polyethylene Glycol Mixtures Passing through Orifices and Slits

Abstract

Recently, a considerable amount of research has been conducted on microbubbles, and accordingly many papers have reported on the research results. For a microbubble/water mixture passed through a capillary tube to which lard oil had been applied, a mass removal rate of 0.3 was found, whereas a rate of 0.9 for only the microbubble/water mixture. Gotoh et al. separated oils in an emulsion by using microbubbles, and Tachibana reported on the medical application of a microbubble/liquid mixture as an ultrasonic contrast agent. Suzuki et al. showed that by suspending microbubbles in liquids, the turbulent structure was changed and the Reynolds stress was lowered. In addition, the drag coefficient was found to be reduced for microbubble/liquid mixtures in rectangular channels and capillary tubes by Murai et al. and Guin et al.. Thus, as seen above, a number of theoretical and applied studies have been previously conducted. However, only microbubble/water mixtures have been typically investigated. Studies on microbubble mixtures in complex liquids, for example, surfactant solutions and polymer solutions, are limited. In general, anomalous and interesting results have been reported from investigations on complex liquids. Okawara et al. measured the pressure drop in slit flows of a wormlike micelle surfactant and found that flow properties changed as the surfactant structure was changed. Ouchi et al. conducted an experiment using an aqueous solution of cetyltrimethylammonium bromide and sodium salicylate, which form wormlike micelles, and reported on the shear induced structure and instabilities. Ushida et al. examined the flow properties of several types of surfactants that form spherical micelles, and found a drag reduction in elongational flows. Hasegawa et al. measured the flow properties and the rheological properties of dilute aqueous solutions of polyethylene oxide. Furthermore, Ushida et al. investigated the pressure drops of surfactant/nanobubble mixtures. However, the study of nanoand micro-bubble/dilute polymer mixtures was rare case. In the present research, a dilute polymer solution in which microbubbles were suspended was passed through different sizes of orifices and slits. The Flow Properties of Microbubble/Polyethylene Glycol Mixtures Passing through Orifices and Slits