Sam Wormley wrote:
Water drops bounce into action (Apr 7)
http://physicsweb.org/article/news/10/4/4
What happens if you let a drop of water fall gently onto a
water-repelling surface? Physicists in France and the Netherlands who
tried the experiment were surprised by what they saw. They found that a
violent, ultra-fine jet of water emerges from the drop, moving at up to
40 times the drop's initial impact speed.
Interesting...
The researchers believe the
unusual behavior is caused by the collapse of an air cavity that is
created when the drop deforms as it hits the surface.
Sort of like a water pistol...
The finding could
have a bearing on industrial applications in which liquids are coated on
to surfaces, such as insecticides being sprayed onto crops or in ink-jet
printing (Phys. Rev. Lett. 96 124501).
Of course, coating a water-based liquid on a hydrophobic surface is a
bit like pissing on a block of paraffin - a fool's errand in the first
place. Coating is usually done with *compatible* substances, not
*antagonistic* ones.
But they have to justify the Universal Research Conclusion ("more
research [i.e. funding] is needed"] in some manner.
Tom Davidson
Richmond, VA
.
