Physicists Use Water To Create 'Knotted Vortex' Loop [VIDEO]
The vortex knot was a mere theory a century ago, but now physicists at the University of Chicago have created a vortex knot in a lab environment for the first time, the university said in a statement.
Creating a vortex knot is like "tying a smoke ring into a knot," the researchers said in the statement. Vortex knots should, in theory, be continual, stable phenomena. "The unexpected thing is that they're not," said Dustin Kleckner, a postdoctoral scientist at UChicago's James Franck Institute. "They seem to break up in a particular way. They stretch themselves, which is a weird behavior."The stretching ends in a reconnection event, where loops elongate, circulate in opposite directions, and then collide.
The researchers were created a knotted vortex loop by designing a wing that resembles a delicately twisted ribbon and brought it to life using a 3D printer. They describe their findings in a paper in Nature Physics this week.
After submerging their masterpiece in water and using electricity to create tiny bubbles around it, the researchers yanked the wing forward, leaving a similarly shaped vortex in its wake.
"We look at plasma physics and turbulence every day in the sun," Study researcher William Irvine said. Additionally, Irvine thinks that "knottedness" is probably a conserved quality - like energy and momentum. "If confirmed, this would deepen our understanding of the dynamics and connections between many disparate fields," Irvine said.
"We don't know if it's true or not, but I think we can finally test this in experiment. There's actually around 50 years of theory on this subject with no clean experiments."
The inspiration for the experiment came after viewing videos of dolphins blowing air-core vortex rings. Researchers replicated what the dolphins were doing using 3D-printed hydrofoils, and they went through about 30 different shapes before they got the vortices they wanted.