Date:November 23, 2015
Source:American Physical Society's Division of Fluid Dynamics
Antarctic penguins live in a bitterly cold place, where the air temperature can drop to -40 degrees Celsius and the winds can hurtle at speeds of 40 meters per second. Although these birds routinely hop in and out of the water in sub-freezing temperatures, they manage to keep ice from coating their feathers.
Now researchers have examined penguin feathers in extreme detail and think they know the penguins' anti-icing trick: a combination of nanostructures and a special oil make Antarctic penguin feathers ultra-water-repelling, or superhydrophobic. Droplets of water on the feathers bead up so much that's it's difficult for heat to flow out of the droplet, and the water will roll off before it has time to freeze.
The researchers will present their findings at the annual meeting of the American Physical Society's Division of Fluid Dynamics, held Nov. 22-24 in Boston, Mass.
Pirouz Kavehpour, a professor in the Department of Mechanical and Aerospace Engineering at UCLA, first got interested in penguin feathers while watching a nature documentary on the famous black and white birds. "I noticed the penguins were coming out of very cold water, and sitting in very cold temperatures, and it was curious that no ice formed on their feathers," he said.
Kavehpour got in touch with Judy St. Leger, a world expert on penguins, who confirmed that indeed no one had ever observed ice on the feather coat of healthy penguins. To find out what the penguins' anti-icing secret was, the two scientists and their colleagues studied penguin feathers, donated by San Diego SeaWorld, using Scanning Electron Microscopy.