Every day, millions of gallons of fuel are lost to a few centimeter wide layer of air. The culprit is the boundary layer, tiny vortices swirling across the surface of every airplane wing and car body moving through the air. Although engineers have steadily slashed aerodynamic friction by slimming down the profile of today’s vehicles, researchers still come up short when it comes to the boundary layer.
This zone of chaotic fluid motion, reports the journal Science, has been virtually impossible to fully understand, predict, or even measure. Legendary Nobel Prize-winning physicist Richard Feynman to call turbulence "the most important unsolved problem of classical physics."
Now supercomputers are turning this invisible layer, just a few centimeters thick, into a more predictable science promising to slash billions of dollars off fuel costs by lowering drag. The computing muscle has emerged to calculate the billions of interactions between a moving surface and the surrounding fluid allowing researchers to run virtual experiments on the aerodynamics of wind turbines (at the National Renewable Energy Lab) or the drag acting on a plane’s wing.
At Australia’s Monash University, two supercomputers — the Multi-modal Australian Sciences Imaging and Visualisation Environment (MASSIVE) and the National Computational Infrastructure in Canberra — are visualizing the patterns and structures in the swirling air by applying massive computing power to the thin layer of turbulence. The results suggest the boundary layer is unpredictable, but not random, says Professor Julio Soria, the director of the Laboratory for Turbulence Research in Aerospace and Combustion.
"We are trying to understand the turbulent boundary layer—the region right next to objects’ surfaces that causes drag on aeroplanes, ships, trains, trucks—all vehicles—as well as the resistance to flow of water, oil and gas in pipes" said Soria in a release. "Now we have better technology, we’re seeing phenomena that we couldn’t see before, and so didn’t account for. As we delve deeper into the structure of the turbulent boundary layer, we find effects that we didn’t even consider."
The ultimate goal is to uncover ways to manipulate the boundary layer, reduce drag and increase aerodynamic efficiency. The potential benefits are enormous. Reducing drag by even a few percentage points would slash billions of dollars off fuel costs, says Soria, citing Airbus’ statistics. Many of the same principles are already being used to design America’s Cup racing yachts and the movement of blood movement through artificial hearts, reports Scientific American.
Flying through the skies may be next.