Bubbles That Break Rules: A Fluid Discovery That Defies Logic
taylorvich writes:
https://phys.org/news/2025-02-fluid-discovery-defies-logic.html
A team led by researchers at UNC-Chapel Hill have made an extraordinary discovery that is reshaping our understanding of bubbles and their movement. Picture tiny air bubbles inside a container filled with liquid. When the container is shaken up and down, these bubbles engage in an unexpected, rhythmic "galloping" motion-bouncing like playful horses and moving horizontally, even though the shaking occurs vertically.
This counterintuitive phenomenon, revealed in a new study published in Nature, has significant implications for technology, from cleaning surfaces to improving heat transfer in microchips and even advancing space applications.
These galloping bubbles are already garnering significant attention: their impact in the field of fluid dynamics has been recognized with an award for their video entry at the most recent Gallery of Fluid Motion, organized by the American Physical Society.
"Our research not only answers a fundamental scientific question but also inspires curiosity and exploration of the fascinating, unseen world of fluid motion," said Pedro Saenz, principal investigator and professor of applied mathematics at UNC-Chapel Hill. "After all, the smallest things can sometimes lead to the biggest changes."
In collaboration with a colleague at Princeton University, the research team sought to answer a seemingly simple question: Could shaking bubbles up and down make them move continuously in one direction?
To their surprise, not only did the bubbles move-but they did so perpendicularly to the direction of shaking. This means that vertical vibrations were spontaneously transformed into persistent horizontal motion, something that defies common intuition in physics. Moreover, by adjusting the shaking frequency and amplitude, the researchers discovered that bubbles could transition between different movement patterns: straight-line motion, circular paths, and chaotic zigzagging reminiscent of bacterial search strategies.
"This discovery transforms our understanding of bubble dynamics, which is usually unpredictable, into a controlled and versatile phenomenon with far-reaching applications in heat transfer, microfluidics, and other technologies," explained Connor Magoon, joint first author and graduate student in mathematics at UNC-Chapel Hill.
Bubbles play a key role in a vast range of everyday processes, from the fizz in soft drinks to climate regulation and industrial applications such as cooling systems, water treatment, and chemical production.
Controlling bubble movement has long been a challenge across multiple fields, but this study introduces an entirely new method: leveraging a fluid instability to direct bubbles in precise ways.
One immediate application is in cooling systems for microchips. On Earth, buoyancy naturally removes bubbles from heated surfaces, preventing overheating. However, in microgravity environments such as space, there is no buoyancy, making bubble removal a major issue. This newly discovered method allows bubbles to be actively removed without relying on gravity, which can enable improved heat transfer in satellites and space-based electronics.
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