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2013年11月21日 Nature4 P, L6 U4 U0 a' x! R; D
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A water drop strikes the water-averse wing of a Morpho $ l: L8 F; X/ M
butterfly. There are many uses for surfaces that can stay dry, self-clean or 5 J1 f2 Z, h R' M2 U
resist icing. Liquid drops hitting such surfaces tend to spread out and then
" Q6 k) a2 O8 ~! \$ Q( w" k4 Bretract before finally bouncing. Many applications benefit from minimizing the
# O: Y; _2 g% o4 ]( s4 R" {contact time between drop and surface, which is generally assumed to occur if
' x. Q2 E+ s: S2 F2 cthe impacting drop deforms symmetrically. Kripa K. Varanasi and colleagues now 9 |7 N9 y- |4 x/ u |4 g, P- v$ ~
show that drops bounce off faster from a superhydrophobic surface with a ( e& Z. R! C) I
morphology that redistributes the liquid mass so that it no longer spreads and + D. ^- l' T& Z2 e5 N
retracts symmetrically. Theory and experiments confirm that this strategy ( R' m9 \' e) l
shortens the contact time between a bouncing drop and a surface beyond what was
5 x4 X) f0 [( U; X- E: G2 {: othought possible. Photo: A. T. Paxson, K. Hounsell, J. W. Bales, J. C. Bird 6 u3 r: z! G# L
& K. Varanasi.
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发表于 2013-11-22 18:25
发表于 2013-11-23 19:31
