Research

Mike Hayden

Reversing turbulence

October 31, 2007

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By Carol Thorbes

SFU physicist Mike Hayden (right) is figuring out how to turn back time on turbulence. It’s a feat similar to making the chaotic swirls and eddies of a mountain stream unravel backwards.

While on a sabbatical at Ecole Normale Supérieure in Paris, Hayden and his collaborators succeeded in controlling turbulent dynamics. Physical Review Letters, an international journal, has just published their discovery and the editor highlighted the article as recommended reading.

"Scientists and engineers have studied turbulence for hundreds of years, but until now the idea of trying to quite literally run things backwards has not been an option," says Hayden.

Turbulence describes phenomena such as the wild flow of air in hurricanes and tornados, when large-scale whorls and swirls form and then break up into smaller and smaller eddies until all of the energy dissipates. Think of a smooth sheet of water flowing over the edge of a cliff and then breaking up into a wild and agitated torrent.

Working at temperatures close to absolute zero, Hayden and his colleagues aligned the nuclei of helium atoms and watched as they naturally formed complex, swirling, turbulent patterns. Then, using carefully designed radio signals, they forced those patterns to unwind, whorl by whorl, until order was established once again.

"Running these things backwards gives you a fantastic new tool for trying to understand exactly how turbulence starts and evolves," explains Hayden. "Who knows what this could lead to in terms of practical applications in industry, travel and medicine?"

Given that turbulence creates drag that can slow down cars and airplanes, this type of research could lead to more fuel-efficient vehicles. It could perhaps make golf balls less errant.

"Those dimples on a golf ball create turbulence and actually help it fly further," says Hayden. Still, he says he has no plans to help make planes or golf balls fly backwards.

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