Wed April 11th 2018
15:30 – 16:00
Seminar Special rebounds: reducing the contact time of impacting water drops
Pierre Chantelot


Superhydrophobic materials, that is hydrophobic solids textured at the micron-scale, are able to fully reflect impacting water drops: they spread, recoil and then take off preserving the dryness of the substrate. Millimeter-sized drops bounce off a water-repellent material after a time on the order of 10 ms. That contact time can be large enough to induce freezing of supercooled drops on cold surfaces, large heat transfer or contamination by surfactants so that it is relevant to find new techniques to repel an impacting liquid quicker. We show that the repellency of superhydrophobic materials, defined as a reduction of contact time, can be enhanced by modifying the geometry of the substrate through two examples. (i) Making a water drop impact a point-like defect with size intermediate between that of the microtexture and that of the drop leads to a reduction of contact time by a factor two. (ii) The interplay between the dynamics of a drop and a soft membrane, that gets deformed during impact, allows us to vary the contact time continuously and reduce it up to 70%.
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The 10th Complex Motion in Fluids 2021
Max Planck Gesellschaft
Centre for Scientific Computing