Contaminants Complicate Bubble Bursts
Many natural and industrial processes generate bubbles that burst at an air–liquid interface. This bursting can create liquid jets that break up into small droplets, releasing any biological or chemical contaminants that might be in the bubbles’ proximity. Because these emissions can affect both public health and global climate, it is crucial to better understand how contaminants influence jet dynamics. Now Jie Feng at the University of Illinois Urbana-Champaign and his colleagues have observed jet formation in the lab [1]. The new model they developed accurately predicts both a jet’s thickness and its dependence on the contaminants’ properties.
When an uncontaminated bubble bursts at a liquid surface, the bubble’s thin film ruptures and leaves behind a collapsing cavity. Ripples called capillary waves travel down the sides of this cavity, while undergoing constant damping caused by the liquid’s resistance to their motion. The convergence of these waves at the center of the cavity’s base can then launch a jet into the surrounding air.
To investigate how contaminants might change that process, Feng and his colleagues used a high-speed camera to observe the bursting of oil-coated bubbles at the surface of a glycerin solution. They found that the capillary waves propagating downward in these bubbles encountered an increasingly thick oil layer, which engendered a complex, time-dependent damping. For low-viscosity oil, this feature resulted in a smooth cavity and a narrow jet when the initial coating was thin. When the coating was thick, the result was a perturbed cavity and a wide jet.
Using these findings, the researchers developed an improved model of jet production in contaminated bubbles. They say that this model could advance understanding of processes ranging from atmospheric aerosol formation to pathogen transmission.
–Ryan Wilkinson
Ryan Wilkinson is a Corresponding Editor for Physics Magazine based in Durham, UK.
References
- Z. Yang et al., “Jet size prediction in compound multiphase bubble bursting,” Phys. Rev. Lett. 134, 214001 (2025).