New equation helps unravel turbulence

Dec. 8, 2005
Researchers at The Johns Hopkins University have discovered a mathematical formula that could lead to more-precise computer models of turbulence.

Doctoral student Yi Li and Professor Charles Meneveau conduct turbulence experiments in a wind tunnel at the Johns Hopkins Homewood campus. Photo: Will Kirk/Johns Hopkins University


"This equation gives us a mathematical shortcut to describe a complex characteristic of turbulence called intermittency," said Charles Meneveau, professor of mechanical engineering and director of the Center for Environmental and Applied Fluid Mechanics at Johns Hopkins. "It solves just one piece of the overall turbulence puzzle, but it's a very important piece."

Intermittency refers to abrupt, concentrated changes in the speed of a moving fluid. If the velocity of a fluid is plotted on a graph, these changes look like sharp drop-offs or cliffs, rather than smooth, gentle slopes. These sharp changes occur infrequently within a turbulent flow. But when they arise, they can be quite violent.

This characteristic has been particularly tough to include in computer models of turbulence because representing it numerically requires a huge number of calculations and a mammoth amount of computing power. "Conceptually, we could do it," Meneveau said. "But it's not practical."

Meneveau and doctorial student Yi Li devised a shortcut by tracking two particles as they move with a turbulent flow like two balloons tossed along by a gust of wind. The resulting equation gave them a tool to predict intermittency by merely solving this simple equation rather than having to solve complicated computer models of turbulence. "Ultimately, we believe this will help researchers put together more precise models that could be used to predict weather patterns, movement within bodies of water and even some turbulent events that take place within an internal combustion engine," Meneveau said.

He and his students have been measuring turbulence and intermittency in a Johns Hopkins wind tunnel.

Sponsored Recommendations

Drive systems for urban air mobility

March 18, 2025
The shift of some of our transport traffic from the road to the air through urban air mobility is one of the most exciting future fields in the aerospace industry.

Blazing the trail for flying robots

March 18, 2025
Eight Bachelor students built a flying manipulator that can hover in any orientation and grasp objects. The drone is even more maneuverable than a quadrocopter and was designed...

Reachy 2: The Open-Source Humanoid Robot Redefining Human-Machine Interaction

March 18, 2025
Reachy 2 was designed to adapt to a wide variety of uses thanks to its modular architecture.

maxon IDX: The plug-and-play solution

March 18, 2025
IDX drives combine power with small space requirements - a brushless BLDC motor combined with an EPOS4 positioning controller and a gearhead inside a high-quality industrial housing...

Voice your opinion!

To join the conversation, and become an exclusive member of Machine Design, create an account today!