Onset of entrainment between immiscible liquid layers due to rising gas bubbles

Abstract The phenomenon of the onset of liquid entrainment by gas bubbles rising vertically across the interface between two immiscible liquid layers is addressed both analytically and experimentally. An analytical model is developed which predicts the minimum gas bubble volume necessary to initiate the onset of entrainment. This model predicts that the phenomenon is characterized by a four-region flow regime. The criterion is based upon the bubble wake dynamics and the physical and transport properties of the two liquids. When compared with the experimental data for eight immiscible liquid pairs, the model and the data exhibit excellent agreement.