Split and Unite: How Turbulence Shapes Bubble Populations*

Turbulence exhibits a fascinating duality in its effect on bubble populations, simultaneously driving two seemingly opposing processes: the fragmentation of large, otherwise stable bubbles and the coalescence of smaller ones through collision. This dynamic interplay gives rise to the polydispersed bubble clouds observed in diverse settings, from breaking waves to chemical, biological, and nuclear reactors. At the heart of this phenomenon lies a critical question: What are the characteristic timescales of breakup and coalescence in turbulence? The complexity of this inquiry stems from the vast range of scales involved, spanning from the Kolmogorov scale to individual bubble diameters and up to the turbulence integral scale. In this talk, we introduce a comprehensive experimental framework designed to capture these two multiscale processes. Our approach aims to shed light on the general mechanisms governing deformable objects, including both droplets and bubbles, in turbulent environments, with a particular focus on the timescales and length scales involved in breakup and coalescence events. By elucidating these processes, we seek to contribute to the development of new models capable of accurately capturing bubble and droplet population dynamics in key applications.