Boat cloak will save energy by tricking water

An engineer in the USA has come up with a concept that could increase the efficiency of ships by ‘tricking’ the water around them into staying still by using a […]

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By Tom Gibson

An engineer in the USA has come up with a concept that could increase the efficiency of ships by ‘tricking’ the water around them into staying still by using a ‘fluid flow cloak’. Ships use a lot of energy pushing the water around them out of the way as they move forward.

Yaroslav Urzhumov, Assistant Research Professor in Electrical and Computer Engineering at Duke’s Pratt School of Engineering said: “What our cloak accomplishes is that it reduces the mass of fluid that has to be displaced to a bare minimum.

“We accomplish this by tricking the water into being perfectly still everywhere outside the cloak. Since the water is still, there is no shear force, and you don’t have to drag anything extra with your object. So, comparing a regular vessel and a cloak of the same size, the latter needs to push a much smaller volume of water, and that’s where the hypothesized energy efficiency comes from.”

The engineer’s design would cover a ship’s hull with porous materials. Using tiny pumps in the material, the mechanism would push the flowing water along at various forces.

Mr Urzhumov explains further: “The goal is make it so the water passing through the porous material leaves the cloak at the same speed as the water surrounding by the vessel. In this way, the water outside the hull would appear to be still relative to the vessel, thereby greatly reducing the amount of energy needed by the vessel to push vast quantities of water out of the way as it progresses.”