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Researchers check 70-year theory of turbulence in liquids



As you mix milk in a cup of coffee, you will see the turbulence of fluid in the action – a quick blend that has defied deep scientific understanding.

The collaboration of researchers from the University of Otago in New Zealand and the University of Queensland in Australia began to learn more about the daily turbulence puzzles using the superfluous properties of superfluids, odd quantum fluids that can flow infinitely without friction.

The discovery of this team, published in the journal Science, may have implications for our understanding of quark-gluonic plasma, electrons in solid matter, and the stability of Jupiter's Great Red spots, or can help create more efficient transportation.

Co-author Dr. Ashton Bradley, lead researcher at the Dodd-Walls Photon and Quantum Technology Center, says the group viewed the state of the negative temperature of quantum vortex in the experiment.

"Although they are important for a modern understanding of turbulent fluids, these states have never been observed in nature, they contain significant energy, but they seem to be well-regulated, defying our usual terms of the disorder in statistical mechanics," says Dr. Bradley.

It describes the understanding of fluid turbulence as a challenging problem.

"Despite the long history of research, the chaotic nature of turbulence has deplored deep understanding, so much so that the need for full description is recognized as one of the unresolved" Millennium Problems "of Clay's Mathematical Institute.

"Fluid turbulence plays an important part in our daily lives – about 30 percent of carbon dioxide emissions come from traffic and fluid turbulence plays a significant role. Deeper understanding of turbulence can ultimately help create a more viable world by improving transport efficiency."

An interesting aspect of turbulence is that it has universal properties, meaning that turbulent systems on a scale from microscopic to planet length have similar descriptions and characteristics.

Nobel Prize Laureate Lars Onsager developed the theory of two-dimensional turbulence toys in 1949. Simply put, it is stated that if you add enough energy to the 2D system, turbulence results in the appearance of giant vortexes – just like in the Jupiter atmosphere.

However, his theory directly relates only to superfluids, where the vortices rotate in discrete (quantum) steps and are almost similar to particles.

Seventy years later, Queensland-Otago cooperation watched Onsager's predictions.

Dr. Bradley says they used a high degree of control available at the Bose-Einstein condensation laboratory at Queensland's Queensland Queue Systems Excellence Center, using the first optical manipulation technology.

They have created superfluid by cooling the gas of the rubidium to almost absolute zero temperature and focusing on laser beams. Developed optical techniques allow them to blend whirlpools exactly into the liquid – just as the milk mixes into your coffee.

The author, Dr. Tyler Neely of Queensland, says the "amazing" thing is that the group has achieved this with light and on such a small scale.

"Spine vortexes in our system are only 1/10 of the human blood cell diameter," he says.

One of the most bizarre aspects of Onsager's theory is that the more energy you add to the vortex system, the gigantic whirlpools become more concentrated. It turns out that if the vortex is considered as particle gas moving within the superfluid, the vortex clusters exist in absolutely negative temperature states, below the absolute zero.

"This aspect is really weird. Absolute negative temperature systems sometimes are described as" warmer than hot "because they really want to give up their energy in any normal system at a positive temperature, which also means they are extremely fragile.

"Our study contrasts this intuition by pointing out that since the vortices are sufficiently isolated within the superfluid, clusters of the vortex of negative temperature can last for almost ten seconds," says Dr. Neely.

Scientific work

linked links

University of Otago

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