Using the surface tension of water and a hydrophobic coating on their legs, many insects are able to walk on water. The surface tension acts like an invisible blanket across the top of the water, while the hydrophobic coating on the insects legs means that they are repelled from water molecules, much like the repulsion of two magnets with the same pole. By studying the simple case of a hydrophobic sphere being dropped into water from different heights, Daniel Harris and his team at Harvard University were able to improve our understanding of the mechanism of water-walking and use it to help build water-walking robots.

This video is part of a collaboration between FYFD and the Journal of Fluid Mechanics featuring a series of interviews with researchers from the APS DFD 2017 conference. Sponsored by FYFD, the Journal of Fluid Mechanics, and the UK Fluids Network. Produced by Tom Crawford and Nicole Sharp with assistance from A.J. Fillo.