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ETH Student solves 100-year-old physics puzzle

An EPFL Student has solved a 100-year-old physics puzzle: Why is an air bubble in a narrow vertical tube with liquid rather than ascend? The researchers was able to measure the phenomenon of extremely precise and explain what's going on here.

the physics of everyday life: mineral water with carbonic acid the air bubbles to the surface. This phenomenon can be with the laws of classical physics is easy to explain. But why an air bubble is motionless when it is in a tube with a few millimeters in diameter?

The mechanisms behind this phenomenon, which was described 100 years ago for the first time, are a mystery to this day. Actually, the bubble should not encounter resistance and easy upgrade. Unless the fluid is in motion, wrote to the Federal Institute of technology Lausanne (EPFL) in a message from Monday.

almost 60 years Ago, the scientist Francis Bretherton tried to explain this phenomenon, he focused on the shape of the bubble focus. Other theorists have argued that the reason for the stuck the bubble in an ultra-thin liquid film that is located between the bladder and the inner wall of the tube. None of these theories explain the mechanisms involved fully.

A bubble of air is stuck in a narrow, vertical tube with liquid. Photo: EPFL

Wassim Dhaouadi, Bachelor's Student in the laboratory of John Kolinski at EPFL, was able for the first time, watch the ultra-thin layer between the bubble and the tube wall, measure and their properties to describe. His results he and Kolinski in the journal "Physical Review fluid published". The researchers do not describe that the bubble remains as previously thought, actually in the tube, but extremely slow moving. A movement that is not seen with the naked eye. to watch

the liquid layer, which measures only a few millionths of a Millimeter, used Wassim Dhaouadi and John Kolinski, a so-called interferometric process. This light is directed to the bubble in the tube and the intensity of the reflected light is analyzed. By analysis of the interference between the inner surface of the tube, the reflected light and the bubbles surface reflected light, the researchers were able to measure the layer between the bladder and the tube surface is very precise.

Relevant the results are, for example, for the investigation of phenomena in the movement of fluids in the nano-range, for example, in biological systems, held on the EPFL in the message. (sda)

Created: 02.12.2019, 13:47 PM

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