Water cloak uses electromagnetism to reduce wake and drag

A schematic for a prototype of the proposed water cloaking device (Credit: Yaroslav Urzhumov/Duke University)

The concept was first developed at Duke University in 2011, and in theory works by matching the acceleration of the surrounding water to an object's movement. This would not only increase propulsion efficiency, it would also leave the water around the object largely undisturbed. While the original concept relied on a complex system of small pumps to create the water cloak, today’s version instead uses electromagnetic fields created by wires and coils to move the charged particles found in seawater. The work is described in the journal Physical Review E.

“There are many ways to reduce wake and drag, like surrounding an object with low-friction bubbles, which is actually done with some naval torpedoes," said Yaroslav Urzhumov, adjunct assistant professor of electrical and computer engineering at Duke.

"But there's only so much you can do if you're just applying forces at the surface. This cloaking idea opens a new dimension to create forces around an underwater vessel or object, which is absolutely required to achieve full wake cancellation."