Cloaking Ships To Trick Water

The future ships are going to be cloaked against sonar, but researchers might make the ships cloaked against the water itself by acting as if they are not there.

The Duke University researchers reached a new cloaking system that depends on a new metamaterial can make the water stand still as the ships move through, by reducing water displacement and eliminating the shear force.

Yaroslav Urzhumov, assistant research professor in electrical and computer engineering at Duke, envisions covering the hull of a ship with a three-dimensional lattice of porous metallic materials that would be embedded with tiny pumps. The pumps could force flowing water through at variable rates.
The water surrounding the hull would appear to be still, relative to the movement of the vessel, which would reduce the amount of energy the vessel needs to get through it. When moving through a fluid, a solid object displaces a greater volume of fluid than its own total volume — think of how much effort it requires to drag a thin fishing line through water. So if these shear forces could be eliminated or mitigated, a moving vessel would displace less fluid.
We’ve seen other examples of ship-efficiency water interference tech lately, including a proposal to harness the Leidenfrost effect, wherein a liquid produces an insulating vapor layer when it comes in contact with a solid object that is hotter than its boiling point. That vapor layer could reduce drag, researchers say. But superheating hulls would likely require lots of energy input, lessening any energy savings from the drag reduction.
A lattice-pump system would conceivably be better, because the micropumps wouldn’t need that much power, Urzhumov says — certainly not as much energy as you would need to push an un-cloaked ship through the seas.

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