'Fluid-flow cloak' said to help ships move more efficiently

It comes from the observation that ships expend a great deal of energy pushing the water around them out of the way as they move forward.

‘When you try to drag an object on a fishing line through water, it feels much heavier than the object itself — that’s because you are dragging an additional volume of water with it,’ said project lead Prof Yaroslav Urzhumov of Duke. ‘What our cloak accomplishes is that it reduces the mass of fluid that has to be displaced to a bare minimum.’

While the cloak postulated by Urzhumov differs from other cloaks designed to make objects seem invisible to light and sound, it follows the same basic principles — the use of a man-made material that can alter the normal forces of nature in new ways.

In Urzhumov’s fluid-flow cloak, he envisions the hull of a vessel covered with porous materials — analogous to a rigid sponge-like material — that would be riddled with holes and passages. Strategically placed within this material would be tiny pumps, which would have the ability to push the flowing water along at various forces.