中国的研究者使落下的液滴像芭蕾舞演员一样旋转

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.

當下落的液滴撞击表面时，就像雨滴撞击路面一样，它要么变平并均匀地扩散开来，要么高高溅起。现在，中国的一组研究团队创造了一种表层，能让下落的液体反弹，像一个优雅的舞者一样旋转。

该团队从在铝表面涂不粘的材料开始着手，就像烹饪用具上使用的那种。然后，研究人员设计了几种方案，使非粘着性区域的一部分像正常的“可湿性”表面一样——这会导致水滴四处扩散。

当水滴撞击设计好的表层时，撞击在可湿区域的那一部分水滴停留在表面上，而与拒水区域接触的那一部分水滴则弹回空中。2019年3月5日，研究人员们在《自然》杂志上发表了他们的研究成果，他们发现，这产生了一系列不平衡的力量，这些不平衡的力量不均匀地拉动水滴——在某些部位的力量比在其他部位的要多——并导致水滴“跳舞”。

通过改变可湿区和拒水区的设计，研究人员能够控制水滴的运动，使其滚动、旋转，甚至表现出不同动作的组合。虽然跳舞的水确实让人着迷，但控制液体在表层跳跃的方式也可能有一些实际的用途，比如制造自洁表层或混合不同的材料。

Notes

1. droplet   n. 小滴，微滴

2. ballerina  n. 芭蕾舞女演员

3. aluminum  n. 铝

4. non-adhesive   a. 无粘着力的

5. mesmerize  vt. 施催眠术;迷住