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2013年11月21日 Nature! ~; }2 U0 I3 W- ?: R3 M- e4 X
, G3 J" ^8 j" r0 vA water drop strikes the water-averse wing of a Morpho $ S4 {: Y/ u$ X( @+ O
butterfly. There are many uses for surfaces that can stay dry, self-clean or . Y8 G" m4 f2 ^+ Z# E
resist icing. Liquid drops hitting such surfaces tend to spread out and then / N8 @* m0 T& G
retract before finally bouncing. Many applications benefit from minimizing the
- Q- ~2 I3 b* p: Ycontact time between drop and surface, which is generally assumed to occur if / b( p p. V$ V/ h8 e: v0 E0 n
the impacting drop deforms symmetrically. Kripa K. Varanasi and colleagues now 1 b" K' r( j1 Q4 a& p& }
show that drops bounce off faster from a superhydrophobic surface with a
6 R" Q! P( L3 {$ L& y+ Zmorphology that redistributes the liquid mass so that it no longer spreads and % Z: ?# S A" J' o" R
retracts symmetrically. Theory and experiments confirm that this strategy
8 x1 L! H3 |- E! @4 kshortens the contact time between a bouncing drop and a surface beyond what was
; G. @1 X; m: e: h# T, j f xthought possible. Photo: A. T. Paxson, K. Hounsell, J. W. Bales, J. C. Bird
3 S6 B* h( c9 w4 v B6 p; B& K. Varanasi.
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发表于 2013-11-22 18:25
发表于 2013-11-23 19:31
