SUNGHWAN "SUNNY" JUNG: In nature the rains are falling at a very high speed, sometime you can go up to 10 meter per second. The raindrops is the most dangerous event for the small animals. Humans is walking and then the bowling balls are falling onto the human. There is an analogy the raindrop to the butterfly. So our study is the first study to look at the high speed raindrop interact with a superhydrophobic surface in nature. Superhydrophobic means the-- it will repel the water by having the two tier structures.
One is a microscale, the rough, bumpy structure. And the other is nanoscale, the wax structure. The wax is coated on the surface. And the one thing we find that the-- as the high speed raindrop impact and the spread on the superhydrophobic surface, they reduce the contact time by shattering into smaller pieces. So by having the smaller contact time, it's very important to limit the heat transfer. So they do not lose a lot of heat from the raindrop impact on the body. The second thing is they limit the momentum transfer, so they don't feel much the impact force on the body by reducing the contact time, yeah. There's a huge market for this kind of surfaces.
The biggest concern in the commercial product is the durability. But in nature durability is not a big issue because it is a living organism, so they keep producing the wax from their body like we produce oil on our skin. So they don't care much about the durability. But if you want to do engineering product based on-- inspired by this material, I think durability is the biggest issue.
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Research by Sunghwan "Sunny" Jung looks at how water droplets bounce off “super-hydrophobic” surfaces like insect wings, bird feathers and plant leaves.