Fragmentation in turbulence

From air-sea gas exchange to flotation bioreactors, fragmentation of bubbles, particles, oil droplets in turbulence constitutes one of the most basic and practically important processes in turbulent multiphase flow. Most phenomenological models and simulations for this problem have been developed based on the classical Kolmogorov-Hinze framework, even though some of the key assumptions have never been tested and challenged. In this talk, I will first introduce a new experimental framework that measures the geometry of breaking bubbles and their surrounding turbulence simultaneously in 3D. From this new result, I will discuss two issues that we found in the classical framework: (i) the Kolmogorov’s classical theory of turbulence is not sufficient for quantifying the turbulent stresses on the bubble interface, and (ii) the assumption that the most relevant and energetic scale of the flow is at the bubble diameter is incorrect. Our work underlines the importance of two missing mechanisms and paves the foundation for future studies on the fragmentation of bubbles, droplets, and particles in turbulence.