Physicists have discovered that during intense shaking, air bubbles flee at a rapid pace.

Bubble presence in liquids is a constant aspect of our lives — found in carbonated drinks and air conditioning systems. They are also utilized for industrial applications — in cooling systems, water purification, and chemical production.

Controlling the movement of bubbles has long been a challenging task across various fields. Recently, scientists have managed to harness hydrodynamic instability for precise bubble manipulation. The research team posed a seemingly simple question: can shaking bubbles up and down cause them to move continuously in one direction?

The bubbles did not merely move — they did so perpendicularly to the direction of shaking. When the container is shaken up and down, the bubbles unexpectedly begin to rhythmically "gallop" — bouncing like playful horses, while moving horizontally despite the vertical shaking.

By adjusting the frequency and amplitude of the shaking, the researchers were able to switch between different modes of movement. They now understand how to achieve linear, circular, and chaotic zigzag motions, reminiscent of food-seeking strategies in bacteria. The explanation and the accompanying mathematical calculations related to this phenomenon are published in the journal Nature Communications.

One application of the "galloping" phenomenon is in microchip cooling systems. On Earth, gas bubbles rise from heated surfaces, preventing overheating. However, in space, buoyancy is absent, and this lack of buoyancy makes bubble removal a significant challenge. The new method enables the active removal of bubbles in a gravity-free environment, which could enhance heat transfer in satellites and space electronics.

The newly discovered bubble movement feature can be utilized for surface cleaning. Additional experiments have shown that "galloping bubbles" can clean dusty surfaces. They move in zigzags, similar to a miniature vacuum robot. Scientists hope that controlling bubble movement will lead to new approaches in surface cleaning and targeted drug delivery.

“The new self-propelling mechanism allows bubbles to traverse distances and grants them unprecedented ability to navigate complex liquid networks. This could offer solutions to long-standing issues in heat transfer systems, surface cleaning, and even inspire the creation of new soft robotic systems,” said Saiful Tamim, a research scientist at the University of North Carolina at Chapel Hill (USA).

Controlling bubble movement remains a complex challenge, even though they exist in most liquids in one form or another. The methods available to engineers and researchers for influencing their movement are limited. The researchers' work demonstrates that bubbles can be guided along predictable trajectories using finely tuned vibrations.

“This discovery transforms our understanding of bubble dynamics from unpredictable to a controllable and universal phenomenon with far-reaching applications in heat transfer, microfluidics, and other technologies,” explained Connor Magoon, a graduate student in mathematics at the University of North Carolina at Chapel Hill.