Physicists make 'tractor beam' in water [View all]
I could see this as having a really useful application in containing oil spills.
11 August 2014
Physicists make 'tractor beam' in water
By Jonathan Webb
Science reporter, BBC News
(excerpt)
Simply dropping a cylindrical wave-maker - a bit like a long rolling pin - in and out of the water, gently, produces a predictable set of waves undulating away from the disturbance. The current on the water surface also travels away from the middle of the cylinder.
wave model The wave patterns were filmed and then re-created using computer models
But if the size of the up-and-down movement is increased, that wave pattern breaks up into choppier pulses. At the same time, the central current switches direction, so that something floating near the middle of the tank can be pulled back towards the wave-maker.
As well as this relatively simple "tractor beam" effect, the team created and modelled various other flow changes that meant they could effectively move a ping-pong ball around their tank at will.
"We can engineer surface flows of practically any shape," said Prof Michael Shats, the paper's senior author. "These could be vortices, these could be outward and inward jets - it's a variety of different flow configurations."....
MORE at http://www.bbc.com/news/science-environment-28739368
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