Lagrangian Tracking of Bubbles Entrained by a Plunging Jet
Alexis Goujon

Meeting • 19 November 2019

Abstract
A liquid jet plunging in a pool of the same liquid may entrain air in the form of bubbles. This process has received much interest in the past due to the fundamental fluid mechanics problems it covers and to its numerous applications, especially in bubble-mediated gas exchange. A study of plunging jets was undertaken focusing on low enough air entrainment rate to enable the individual tracking of bubbles. This Lagrangian point of view gives access to the bubbles' trajectories as well as their residence time, a crucial quantity for gas exchange. While individual bubble motion is essentially random (owing to turbulence), average quantities were found to behave coherently with respect to the jet's parameters. The project comprises experimental work, image processing, bubble tracking and numerical simulations. The presentation will place a special emphasis on the tracking algorithm specially designed for this study. https://doi.org/10.1103/APS.DFD.2018.GFM.V0073