Three-dimensional measurements of bubbles and droplets interface dynamics in homogeneous isotropic turbulence

In this work, we discuss the deformation and breakup mechanisms of bubbles and oil droplets dispersed in homogeneous isotropic turbulence (HIT). The turbulence is created in an octagonal horizontal water tank by two opposing jet arrays, which produce a Taylor-microscale Reynolds number up to 1000 and correspondingly high energy dissipation rates of O(1) m²s^-3. We resolve the interplay between phases by coupling statistics from 3D-Particle Tracking Velocimetry with the full 3D reconstruction of the droplet/bubble topology; our imaging system is equipped with six high-speed cameras and backlight illumination. In this case study, we compare the interface dynamics of air bubbles and oil droplets with different viscosity ratios. Inner viscosity effects are illustrated by significant stretching of the fluid particles, forming thin filaments before the breakup. Experimental data is provided on the correlation between external turbulence forcing and interface morphology. Furthermore, we discuss the timescales and instabilities involved in the breakup process, aiming to generate a homogeneous data source on this problem of fundamental importance across various environmental and industrial applications.