Jumping droplets for cooling applications

One of the "hottest" applications of what I am doing at The University of Edinburgh as a part of my PhD is the "coalescence induced jumping of droplets for cooling purposes over specially treated surfaces". By "specially treated surfaces", I mean super-hydrophobic surfaces upon which droplets (mainly water) sit like a ball sits on a floor.

When two such neighboring droplets coalesce, the final droplet will have a smaller surface area than the combined areas of the first two. This reduction in the area supplies some energy for the final droplet to jump off the surface. That's the physics (certainly not all!) behind it.

I know what the applications of this interesting phenomena are, but it's really difficult to explain them just using words to friends, parents etc. That's when I found this video made by a research team from Duke University.









Apparently, insects like Cicada are already experts in this field. One of the main advantages of this mechanism is that you do not need any pump to make the​water reach a height above. This potentially avoids the involvement of any moving parts in the cooling mechanism and we do not have to worry about any frictional losses. Further details can be found at http://pratt.duke.edu/news/cooling-droplets.

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Recent Publications

R Pillai, JD Berry, DJE Harvie, MR Davidson (2017) Electrophoretically mediated partial coalescence of a charged microdropChemical Engineering Science, 169: 273-283. (access here)

JF Xie, BY Cao (2017) Fast nanofluidics by travelling surface wavesMicrofluidics and Nanofluidics, 21: 111 (access here)

AP Gaylard, A Kabanovs, J Jilesen, K Kirwan, DA Lockerby (2017) Simulation of rear surface contamination for a simple bluff bodyJournal of Wind Engineering and Industrial Aerodynamics, 165: 13-22. (full paper here)