Modern airplanes use up to half their fuel to overcome the drag caused by turbulence at the surface of an airplane.

In 2010, Professor Ivan Marusic’s team of engineers at the University of Melbourne became the first in the world to predict and model the behaviour of the eddies that cause this drag—known as boundary layer turbulence. And now they are trying to control them.

“Even a five per cent reduction could save billions of dollars, and millions of tonnes of carbon dioxide,” says Ivan, “which is a big deal to aircraft operators like Qantas.”

Using a purpose built 27m wind tunnel—where the entire floor is the testing surface—Ivan’s team get a unique perspective on how these eddies change and interact as they pass along a surface.

What they found was that current models of turbulence are overly simplistic.

“They average out the effects of the eddies over time and space. In reality, there are eddies at the metre scale, and others at the micrometre scale, which are all interacting with each other in time and space,” Ivan says.

“We worked out how to predict these interactions, but the next step is trying to control them.”

It was believed that in order to reduce drag you would have to control the smallest eddies, which is impractical given the tiny scales they occur at.

But Ivan and his team have recently discovered a relationship between these eddies, meaning that they can now control the smaller eddies by changing the larger ones.

For more information:

Department of Mechanical Engineering, The University of Melbourne
Professor Ivan Marusic
+61 3 8344 6872
imarusic@unimelb.edu.au
www.eng.unimelb.edu.au/research/optimisation/reducing-turbulence

Banner image: What happens when earth, wind, and sea meet? Inside the University of Melbourne’s new wind tunnel
Credit: Joe Vittorio