Turbulent Flows Take a Surprising Spin in a Core-Inspired Experiment – ScienceDaily


A team of physicists has discovered a new role for a specific type of turbulence – a finding that sheds light on flows of fluids ranging from Earth’s liquid core to boiling water.

Research that appears in the journal Proceedings of the National Academy of Sciencescentered on turbulent convection – the movement of fluids when heated from below.

“Our experiments reveal complex motions between free body and convective heat flow,” says John Zhang, professor of mathematics and physics at NYU and NYU Shanghai, senior author of the paper.

The study, which also included Caizhi Wang, a researcher in the NYU Department of Physics, focused specifically on Riley-Benard convection — a type of convection driven by temperature differences.

In their experiments, conducted at the Joint Research Institute at NYU Shanghai, the paper’s authors used a cylindrical container filled with water, which they then heated from the bottom, creating convection flows. The resulting turbulent flows interacted with a suspended solid (a rectangular plate) that moved freely inside the container—a situation that allowed the researchers to better study how the turbulent flows interacted with the solid structures inside.

“It’s surprising that the system has become somewhat well-behaved,” Zhang notes. “We noticed smooth rotation of the streams and free crucifixion.”

Their results showed that turbulent convective flows, along with the solid, can move in two directions—one clockwise and the other counterclockwise—with the co-rotation speed increasing with the intensity of the convection. More so, their rotation can sometimes switch directions, due to turbulence.

“The research, inspired by the rotation of Earth’s inner core as it interacts with the convective liquid core, captures the interaction between a turbulent flow and a freely moving body within the flow,” Chang explains. “The results confirm that turbulence can be calmed by interaction with solids. They also remind us that convective force may play more important roles within the planet.”


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