Tag: bursting

Viscoelasticity and Bubbles
Bursting bubbles enhance our drinks, seed our clouds, and affect our health. Because these bubbles are so small, they’re easily affected by changes at the interface, like surfactants, Marangoni effects, or, as a recent study shows, viscoelasticity.
A bubble released in pure water pops at the surface, creating a rebounding jet and a daughter droplet.
In clean water, a bubble’s burst generates a rebounding jet that shoots off one or more daughter droplets, as seen in the animation above. But when researchers added proteins that modify only the water’s surface, they found something very different. As seen below, the bursting bubble no longer generated a jet, and, instead of forming droplets, it made a single, tiny daughter bubble. The difference, they found, comes from the added viscoelasticity of the surface. The long protein molecules resist getting stretched, which damps out the tiny waves that surface tension usually produces on the collapsing bubble cavity. (Image and research credit: B. Ji et al.; submission by Jie F.)
When the surface of water is viscoelastic, a bursting bubble creates no jet and a daughter bubble instead of a drop.
October 26, 2023
Oil-Covered Bubbles Popping
When bubbles burst, they release smaller droplets from the jet that rebounds upward. Depending on their size, these droplets can fall back down or get lofted upward on air currents that spread them far and wide. Thus, knowing what kind of bubbles produce small, fast droplets is important for understanding air pollution, climate, and even disease transmission.
The jet from a bubble of clean water is broad and slow, releasing fewer and larger drops.
In a recent study, researchers compared droplets made by clean, water-only bubbles, and the ones generated from water bubbles with a thin layer of oil coating them. The clean bubbles created jets that were broad and relatively slow moving; this motion produced a few large drops that quickly fell back down.
The jet from an oil-covered bubble is skinny and fast-moving. It produces many small droplets.
In contrast, the oil-slicked bubbles made a narrow, fast-moving jet that broke into many small droplets. These droplets could stay aloft for longer periods, indicating that contaminated water can produce more aerosols than clean. (Image credit: top – J. Graj, bursting – Z. Yang et al.; research credit: Z. Yang et al.; submitted by Jie F.)
May 18, 2023
How Large Particles Get in Sea Spray
When bubbles burst at the ocean’s surface, they eject droplets that can carry high concentrations of contaminants like pollutants, viruses, and microplastics. Previous theories posited that only particles smaller than the microlayer surrounding the bubble could make their way into these drops, but new work shows otherwise.
As bubbles rise to the surface, they carry particles on their surface, collecting them to a concentration that’s even higher than the surrounding seawater. But which particles make it into the air depend on the details of what happens when the bubble pops. Previously, researchers assumed that the thin microlayer of fluid surrounding the bubble was uniform, but that turns out not to be the case. As the bubble pops, some regions of the microlayer stretch and thin, while others grow thicker. The thicker the microlayer, the larger the particles it can pull along. In their single-bubble experiments, the researchers found that 15- and 30-micrometer plastic beads — representing oceanic microplastics — appeared in high concentrations in ejected droplets.
This animated simulation shows how fluid along the edge of a bubble makes its way into ejected droplets. Green particles indicate fluid from the left half of the bubble; blue shows fluid from the right side.
Environmental scientists are keen to understand these mechanisms because they link our oceans and atmosphere, potentially affecting rainfall, pollution spread, and epidemiology. (Image, video, and research credit: L. Dubitsky et al.; via APS Physics)
March 21, 2023
“Radiolarians”
“Radiolarians” is a short film by artist Roman De Giuli using ink, alcohol, and oil. Much of the fluid motion involves break-up into droplets. The effects appear to rely heavily on Marangoni bursting, the physics of which you can learn about in this previous post. (Image and video credit: R. De Giuli)
March 19, 2021
Popping an Oil Balloon
Oil and water don’t mix — or at least they won’t without a lot of effort! In this video, we get to admire just how immiscible these fluids are as oil-filled balloons get burst underwater.
Visually, the two bursts are quite spectacular. In the first image, the initial balloon has a sizeable air bubble at the top, which rises even more rapidly than the buoyant oil, creating a miniature, jelly-fish-like plume that reaches the surface first. The large oil plume follows, behaving similarly to the balloon burst without an added air bubble.
The last of the oil in both cases comes from a cloud of smaller droplets formed near the bottom of the balloon. Being smaller and less buoyant, these drops take a lot longer to rise to the surface and remain much closer to spherical as they do. I suspect these smaller droplets form due to the forces created by the fast-moving elastic as it tears away. (Video and image credit: Warped Perception)
August 7, 2020
Capsule Impact and Bursting
Nature and industry are full of elastic membranes filled with a fluid, from red blood cells to water balloons. A new study looks at how these capsules deform — and sometimes burst — on impact. The researchers created custom elastic shells that they filled with various fluids like water, glycerol, and honey, then used the impacts to build a model of capsule deformation.
They found that there’s significant overlap between droplet impacts and capsule impacts, with a few key differences; instead of surface tension, capsules resist deformation through their elastic shell’s surface modulus — a combination of its elasticity and thickness. Capsules, unlike droplets, can also burst. To study this, the researchers used water balloons, which they were able to pre-stretch more easily than their custom shells. They found that their model could accurately predict the conditions under which the balloons burst.
The authors hope the model will be helpful both in designing capsules intended to burst — like a fire-fighting projectile — and in creating safety measures to prevent capsule burst — like car-crash standards that protect from organ damage. (Image and research credit: E. Jambon-Puillet et al.; via Physics World; submitted by Kam-Yung Soh)
May 8, 2020