Dynamics of bubble breakup under turbulent flow conditions

Journal article, 2025

This study provides unique insights into the dynamics of bubble deformation and breakup under turbulent flow conditions, utilizing both experimental measurements and high-resolution simulations and unveils information that has been previously unattainable with current methods. The simulations are rigorously validated against experimental data obtained under identical hydrodynamic conditions, and enable analyzes of the interfacial dynamics, breakup time scales, daughter size distributions, and internal flow mechanisms, crucial for advancing future model development. Overall, the dynamic deformation and statistical data show very strong agreement with experimental measurements and reveal an inherent stochastic behavior of bubble breakup due to turbulent interactions. For the first time, details of the internal flow mechanism during bubble breakup have been resolved, revealing development of flow velocities up to 30 times greater at the bubble neck compared to the mean bubble velocity. Analysis reveals that the characteristic internal redistribution flow occurs within a fraction of a millisecond, necessitating a temporal resolution of 20,000 frames per second. The development of an accelerating internal flow is quantified throughout the process until a sudden termination of the flow occurs due to the rapidly shifting balance of stresses at the interface. This ultimately leads to the breakup and formation of unequal sized daughter fragments, approximating a U-shaped distribution, with consistent results in both experimental and simulation data. Evidence suggests that bubble breakup at higher Weber number can form satellite fragments like what is known from droplet breakup, but these are likely beyond the resolution capabilities of the most advanced experimental setups documented in single bubble breakup literature. Consequently, simulations offer a more comprehensive understanding of bubble dynamics, surpassing current experimental capabilities due to their superior temporal and spatial resolutions and the absence of complications from light reflection and refraction at interfaces. The details and quantifications presented in this study are anticipated to contribute significantly to the development of refined breakup kernels.