Bubble breakup in turbulence

We present the design and characterization of an opposing-pumps water turbulence tank used to study the dynamics and breakup of air bubbles in turbulence. The tank is inspired by previous larger-scale setups, but differs from these in that the generated turbulence must be strong enough to break millimeter-scale bubbles. Particle image velocimetry is employed to analyze the flow and optimize the trade-off between turbulence intensity maximization and mean flow minimization. Bubbles are injected at a controlled air flow rate through needles of various sizes and their dynamics and breakup in the turbulence tank are measured with high-speed imagery. We discuss the dynamical breakup of bubbles in turbulence, using the bubbles' three-dimensional trajectories, deformation, and breakup locations. We present data on the breakup threshold, time scale, and child bubble distribution for various injected bubble sizes.