New insights into stratified line fountains published in JFM

A part of my PhD research, which focussed on turbulent line fountains has now been published in the Journal of Fluid Mechanics (JFM)! This work tackles a fascinating gap in our understanding: how fountains behave when they encounter a lateral density difference, a scenario critical to real-world applications like air curtains and underwater bubble screens.

While the dynamics of fountains in uniform environments are well-documented, their interaction with lateral stratification remained an open problem. By combining high-fidelity Large Eddy Simulations (LES) with time-resolved Particle Image Velocimetry (PIV) experiments, we uncovered some surprising behaviors. Most notably, we discovered a new scaling law for the fountain’s trajectory that follows a steep power law, driven by a unique bidirectional forcing and adverse pressure gradient at the impingement surface.

Perhaps the most exciting finding is that lateral stratification doesn’t just alter the flow path; it actively energizes the fountain’s natural flapping mode which was more prominent in experiments. This unsteadiness leads to a significant increase in fluid entrainment: up to 20% more than in uniform cases. These insights not only deepen our theoretical grasp of stratified turbulence but also offer practical implications for optimizing the sealing effectiveness of air curtains.

This project was a true synergy of numerical and experimental approaches, and I’m grateful to my supervisors and collaborators for their contributions. You can read the full paper here. I’d love to hear your thoughts or discuss how these findings might apply to your own work in fluid dynamics!