Flow properties of microbubble mixtures and complex fluids passing through micro-apertures

Abstract

The pressure drops were measured for water, microbubble/water mixtures, and complex fluids (spherical micelle surfactant solution and polymer solution) in flows through micro-apertures (micro-orifices, circular pores, and hexagonal pores). For water, agreement between the resultant pressure drops and the predictions of the Navier- Stokes equation was obtained. For microbubble/water mixtures, drag reduction effect was suggested over a Reynolds number of about 1.0 × 101 in micro-orifice flows. Surfactant solutions exhibited the same results as microbubble/water mixtures. For polymer solutions, significant drag reduction was shown. Moreover, a drag reduction effect, which was independent of the used test fluids, was observed for Reynolds numbers over 1.0 × 101 in the flow through circular pores and hexagonal pores. To explain this phenomenon, the size effect, visco-elastic property, electric interaction, and interfacial tension are considered. The results suggest that electric interaction at the wall (interfacial tension) is a contributing factor. In addition, drag reduction rates were estimated.