In many situations, engineers want to minimize the contact of droplets of water or other liquids with surfaces they fall onto.
In many situations, engineers want to minimize the contact of droplets of water or other liquids with surfaces they fall onto. Whether the goal is keeping ice from building up on an airplane wing or a wind turbine blade, or preventing heat loss from a surface during rainfall, or preventing salt buildup on surfaces exposed to ocean spray, making droplets bounce away as fast as possible and minimizing the amount of contact with the surface can be key to keeping systems functioning properly.
Now, a study by researchers at MIT demonstrates a new approach to minimizing the contact between droplets and surfaces. While previous attempts, including by members of the same team, have focused on minimizing the amount of time the droplet spends in contact with the surface, the new method instead focuses on the spatial extent of the contact, trying to minimize how far a droplet spreads out before bouncing away.
The new findings are described in the journal ACS Nano in a paper by MIT graduate student Henri-Louis Girard, postdoc Dan Soto, and professor of mechanical engineering Kripa Varanasi. The key to the process, they explain, is creating a series of raised ring shapes on the material’s surface, which cause the falling droplet to splash upward in a bowl-shaped pattern instead of flowing out flat across the surface.
Read more at Massachusetts Institute of Technology
Image: Droplets that land on a specially prepared surface with tiny ring-shaped patterns splash upward in a bowl shape, as seen in this photo, instead of spreading out over the surface, thus minimizing the water’s contact with the surface. CREDIT: Henri-Louis Girard, Jim Bales, and Kripa Varanasi
