When spinning, the droplets' shape becomes triangular

Dec 11, 2008 15:10 GMT  ·  By

Water droplets are pretty common in everyday life, so not many people give them a thought beyond that of wiping them off their hands or, at best, that of using them as a model for an artistic photography. But the fluid mechanics has a lot of interesting things to show and to teach us. This is why scientists still spend their time trying to find more about it. A recent laboratory study, for instance, has revealed how suspended water droplets can act based on the same principles as atoms or black holes.

A team from the University of Nottingham in the UK, led by Richard Hill, found that the droplets answer to the same physical laws that cause their surface tension to hold them together as other objects in nature, from the tiny atoms to the colossal mysterious phenomena known as the black holes. And perhaps knowing more about the behavior of water droplets could shed more light on that of the previously mentioned objects. The event horizon of a black hole is often perceived as a "stretched" membrane with a surface tension.

 

The researchers made the droplets levitate by means of a technique named diamagnetism, which caused the drops to develop a magnetic field of their own that counteracted the external one that was imposed on them by the team, and the repulsive force they generated was enough to cancel the pull of gravity. The group of experts also made the droplets spin by inserting two miniature electrodes that generated an electric field.

 

Much to their surprise, when the one-centimeter diameter droplets achieved rotational velocities of some three revolutions every second, their shape, as viewed from straight above, turned into that of a triangle, similar to the form of some objects in the Kuiper Belt. It’s the first time this phenomenon has been observed or created in a laboratory. "The breakthrough in this work is the ability to reproduce, in a simple table-top experiment, 100 years of theoretical work in fluid dynamics," shared Vitor Cardoso from the University of Mississippi, as cited by New Scientist.