For airplanes and other vehicles like it, it only takes a split second for a drop of water to freeze, which might cause system malfunction, which thus creates safety risks for the plane. In order to prevent this, people at the MIT found out a way “to make water-repellant surfaces better shed a soaking”.
The new method builds on research from about six years ago when it was discovered that small macroscopic features added to a surface, like a series of nearly imperceptible ridges, helped break up a water drop’s shape and symmetry as it recoiled from an impact, increasing the speed at which it bounced away from that surface. The amount of time a drop was in contact with a surface was reduced by about 40 percent, which also reduced the amount of time there was for thermal exchange. In other words, it reduced the risk of raindrops having enough time to turn to ice.
When a droplet hits the macroscopic structure it spreads out and fills it, but only until it hits the bowl’s edge, at which point it’s deflected upward and ultimately away from the surface. The amount of spread isn’t being reduced, but since it’s being deflected away there’s minimal interaction between it and the treated surface—which was the ultimate goal here. The effectiveness of this structure does depend on its size, and the size of the droplet that’s making an impact, but even if every drop isn’t quickly bounced away, overall there’s still a definite improvement.
More details of this study on Gizmodo.
(Image Credit: Henri-Louis Girard, Jim Bales, Kripa Varanasi/ MIT News)