中國的研究者使落下的液滴像芭蕾舞演員一樣旋轉(zhuǎn)

景一

When a falling liquid droplet hits a surface， like a raindrop hitting pavement， it either flattens and spreads out evenly， or produces a sharp-edged splash. Now， a team of Chinese researchers has created a surface which allows the descending liquid to rebound and swirl around like a graceful dancer.

The team began by coating an aluminum3 surface with nonstick material， like the kind used on cooking utensils. The researchers then created several designs by covering portions of the non-adhesive4 area so that it would act like a normal， “wettable” surface—meaning it would cause the falling droplets to spread around.

When a water droplet hit the patterned surface， the part of it that hit the wettable areas stayed on the surface， while the portions that came in contact with the waterproof areas sprang up back in the air. According to the researchers， who published their study in the journal Nature on March 5， 2019， this created a set of unbalanced forces that pulled unevenly at the water droplet—more in some parts than in others—and caused it to “dance”.

By varying the designs of the wettable and water-repellant areas， the researchers were able to control the motion of the droplet and make it roll， twirl and even perform a combination of different actions. While the dancing water is certainly mesmerizing5 to watch， controlling how liquid leaps off a surface may also have some practical applications—like creating self-cleaning surfaces or mixing different materials.

當(dāng)下落的液滴撞擊表面時，就像雨滴撞擊路面一樣，它要么變平并均勻地擴散開來，要么高高濺起?，F(xiàn)在，中國的一組研究團隊創(chuàng)造了一種表層，能讓下落的液體反彈，像一個優(yōu)雅的舞者一樣旋轉(zhuǎn)。

該團隊從在鋁表面涂不粘的材料開始著手，就像烹飪用具上使用的那種。然后，研究人員設(shè)計了幾種方案，使非粘著性區(qū)域的一部分像正常的“可濕性”表面一樣——這會導(dǎo)致水滴四處擴散。

當(dāng)水滴撞擊設(shè)計好的表層時，撞擊在可濕區(qū)域的那一部分水滴停留在表面上，而與拒水區(qū)域接觸的那一部分水滴則彈回空中。2019年3月5日，研究人員們在《自然》雜志上發(fā)表了他們的研究成果，他們發(fā)現(xiàn)，這產(chǎn)生了一系列不平衡的力量，這些不平衡的力量不均勻地拉動水滴——在某些部位的力量比在其他部位的要多——并導(dǎo)致水滴“跳舞”。

通過改變可濕區(qū)和拒水區(qū)的設(shè)計，研究人員能夠控制水滴的運動，使其滾動、旋轉(zhuǎn)，甚至表現(xiàn)出不同動作的組合。雖然跳舞的水確實讓人著迷，但控制液體在表層跳躍的方式也可能有一些實際的用途，比如制造自潔表層或混合不同的材料。

Notes

1. droplet? ?n. 小滴，微滴

2. ballerina? n. 芭蕾舞女演員

3. aluminum? n. 鋁

4. non-adhesive? ?a. 無粘著力的

5. mesmerize? vt. 施催眠術(shù);迷住