Air bubbles crossing a stratified water-diesel fuel interface

Abstract

This study examines the behavior of a single air bubble moving through a stratified interface between two liquid phases: purified water as the denser liquid and diesel fuel as the lighter counterpart. The study investigates the impact of the upper liquid's height on bubble behavior, particularly under low gas flow rates, using high-speed video imaging. The experimental findings unveil two distinct scenarios: stable and unstable regimes. In stable conditions, the bubble follows a linear trajectory, simultaneously transferring some of the denser liquid into the lighter phase. Conversely, under unstable conditions, the bubble undergoes oscillations, navigating a zigzag or spiral path. The study also explores the correlation between the upper liquid height and the deformation and division of the dragged volume. This comprehensive investigation sheds light on the intricate interplay between liquid heights and bubble dynamics at liquid-liquid interfaces.