Droplets break a theoretical time barrier on bouncing
Those who study hydrophobic materials — water-shedding surfaces such as those found in nature and created in the laboratory — are familiar with a theoretical limit on the time it takes for a water droplet to bounce away from such a surface. But MIT researchers have now found a way to burst through that perceived barrier, reducing the contact time by at least 40 percent.Their finding is reported in a paper in the journal Nature co-authored by Kripa Varanasi, the Doherty Associate Professor of Mechanical Engineering at MIT, along with James Bird, a former MIT postdoc who is now an assistant professor of mechanical engineering at Boston University, former MIT postdoc Rajeev Dhiman, and recent MIT PhD recipient Hyukmin Kwon.“The time that the drop stays in contact with a surface is important because it controls the exchange of mass, momentum, and energy between the drop and the surface,” Varanasi says....