Entrainment dynamics of a Taylor bubble crossing stratified liquid-liquid interface

The present study investigates the rise of Taylor bubbles through a stratified interface in a vertical pipe. Different fluidic stages of the bubble during bypass from one liquid layer to another are highlighted. Splitting and unified bypass of the Taylor bubble is observed depending upon the combination of heavier and lighter fluid properties. Quantity in entrainment is found to be less in the case of bubble splitting at the liquid-liquid interface than in the unified bypass case. Effects of the viscosity ratio and density ratio of heavier to lighter liquids, the interfacial tension between liquids, bubble size, and trailing bubble on the entrainment dynamics have been investigated. Entrainment of the heavier fluid decreases with the decrease in the viscosity ratio and the bubble size. Whereas, with the increase in the interfacial tension, the maximum entrained volume increases and decreases with an increase in the density ratio. In the presence of a trailing Taylor bubble, entrainment is decreased by 40 % compared to the isolated Taylor bubble's passage through the liquid-liquid interface. (c) 2023 Elsevier Ltd. All rights reserved.