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2013年11月21日 Nature |) P8 H* c5 Z
) U/ o" N# T) K( N9 ^$ kA water drop strikes the water-averse wing of a Morpho
' q0 B* e# J/ B( W2 [' hbutterfly. There are many uses for surfaces that can stay dry, self-clean or ' t2 A' X) q' L3 m# m# o
resist icing. Liquid drops hitting such surfaces tend to spread out and then 9 w' j( s$ P0 X2 t& s7 U- w0 x
retract before finally bouncing. Many applications benefit from minimizing the 3 k0 ~3 h. j: x0 D
contact time between drop and surface, which is generally assumed to occur if 9 M8 L. D; g/ d' o K
the impacting drop deforms symmetrically. Kripa K. Varanasi and colleagues now 4 _2 w! d9 G9 Z+ J* ?: Q
show that drops bounce off faster from a superhydrophobic surface with a
) X9 `$ Q7 e8 o3 N4 Nmorphology that redistributes the liquid mass so that it no longer spreads and * y8 L: A/ @3 @: U! Z" }, U
retracts symmetrically. Theory and experiments confirm that this strategy
3 J9 L c$ }5 {0 S+ Kshortens the contact time between a bouncing drop and a surface beyond what was $ ]2 ^; e/ U9 W/ c* q
thought possible. Photo: A. T. Paxson, K. Hounsell, J. W. Bales, J. C. Bird
4 _6 H4 N$ V; \- T& K. Varanasi.
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发表于 2013-11-22 18:25
发表于 2013-11-23 19:31
