Owls are among the most silent hunters in nature, thanks to their feathers. The leading edge of the wing, shown in the bottom part of the photo, has a serrated comb-like edge, which breaks flow over the wing into small vortices, which are quieter than larger ones. The fringe-like trailing edge breaks the flow up further and helps absorb the sound produced by the turbulence. The fluffy feathers along the owl’s body can also help muffle noise. Researchers are investigating ways to use these techniques to quiet aircraft. # (via jshoer)
Tag: vorticity
Steam Devils
The formation of the ethereal steam devil is quite similar to the formation of a fire tornado. In this case, the first frost of the season cooled air temperatures substantially below the temperature of the water of the lake, creating conditions for steam and for updrafts of rising, warmer air. A slight breeze across the lake is enough to create pockets of vorticity, which stretch due to the updrafts and intensify due to conservation of angular momentum. This creates the narrow spinning vortex filaments that pull steam up and dance across the lake’s surface. #
Fire Tornado Formation
The phenomenon of a fire tornado caught our attention recently after the BBC published footage of one in Brazil. While it may look like the fiery wrath of a god, the fluid dynamics of a fire tornado are relatively simple (see figure above). Still, they make for some pretty wild video.
Spore-Spreading via Vortex
As it turns out, animals aren’t the only ones to have figured out the usefulness of vortex rings. A team of physicists and biologists have captured peat moss using vortex rings to project their spores to a height where the wind will catch and carry them further afield. #
Dolphins Making Bubble Rings
Marine animals know more about fluid dynamics than we might think. Dolphins make games out of blowing vortex rings (a.k.a. bubble rings) and tossing them around. You can try, too, next time you’re at the pool!
Vortex Cannon
Ever wonder if the Big Bad Wolf could really blow those pigs’ houses down? If he’d gone with a vortex cannon, maybe he’d have a chance.
