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posted by mrpg on Thursday December 14 2017, @08:30AM   Printer-friendly
from the in-australia-too? dept.

Less Noise, Less Drag:

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while simultaneously helping it avoid detection.

The idea originated at Duke University in 2011 when researchers outlined the general concept. By matching the acceleration of the surrounding water to an object's movement, it would theoretically be possible to greatly increase its propulsion efficiency while leaving the surrounding sea undisturbed. The theory was an extension of the group's pioneering work in metamaterials, where a material's structure, rather than its chemistry, creates desired properties.

Six years later, Yaroslav Urzhumov, adjunct assistant professor of electrical and computer engineering at Duke, has updated the theory by detailing a potential approach. But rather than using a complex system of very small pumps as originally speculated, Urzhumov is turning to electromagnetic fields and the dense concentration of charged particles found in saltwater.

Dean Culver, Yaroslav Urzhumov. Forced underwater laminar flows with active magnetohydrodynamic metamaterials. Physical Review E, 2017; 96 (6) DOI: 10.1103/PhysRevE.96.063107


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  • (Score: 4, Informative) by MostCynical on Thursday December 14 2017, @09:02AM (6 children)

    by MostCynical (2589) on Thursday December 14 2017, @09:02AM (#609622) Journal

    Hmm..
    "Urzhumov says that for an actual ship or submarine to ever use such a device, it would need a nuclear reactor to power it, given the enormous energy requirements to cloak an object of that size. That does not mean, however, that a smaller diesel vessel could not power a smaller cloaking device to shield potentially vulnerable protrusions from detection."

    https://pratt.duke.edu/news/water-cloak [duke.edu]

    Tl;dr: needs HUGE amounts of power to work.

    --
    "I guess once you start doubting, there's no end to it." -Batou, Ghost in the Shell: Stand Alone Complex
    • (Score: 3, Interesting) by Runaway1956 on Thursday December 14 2017, @09:20AM (2 children)

      by Runaway1956 (2926) Subscriber Badge on Thursday December 14 2017, @09:20AM (#609630) Journal

      Well now, most submarines already HAVE nuclear reactors. So, speaking as a destroyer man, WTF? We can't track them with sonar anymore? Tracking subs has always been as much a matter of luck, as skill and technology. Our ship had a trick of it's own, which tipped the odds in our favor, most of the time - a towed array passive sonar, which could be dipped below the thermocline, among other things. Still - as good as our tech, as good as our sonar techs were, there WAS luck involved. We could drive over a stealthed sub multiple times before finally seeing, if their crew was good. Of course, it only took a single sneeze to give away their position . . .

      It should be noted that even the sounds of a "silent" nuclear reactor can be picked up. There are many pumps in the system. Some of those pumps are for reactor cooling water, other pumps for moving ballast, and yet more pumps to take on or expel ballast water. All of them make sounds, however slight. So, silence the screw and propellor, you've still got noises going on. Are these guys suggesting that none of those sounds will make it past the barrier they have created?

      • (Score: 3, Interesting) by MostCynical on Thursday December 14 2017, @09:26AM

        by MostCynical (2589) on Thursday December 14 2017, @09:26AM (#609631) Journal

        If it is only the wake and drag they are reducing, then there would be no change, unless something weird happens at the boundary between the electrohydrodynamic water and the rest of the ocean.

        This "apparatus" covers the whole submerged parts of any vessel, so without power, any vessel so equipped is going to be a juicy, slow target.

        --
        "I guess once you start doubting, there's no end to it." -Batou, Ghost in the Shell: Stand Alone Complex
      • (Score: 3, Informative) by PinkyGigglebrain on Thursday December 14 2017, @07:25PM

        by PinkyGigglebrain (4458) on Thursday December 14 2017, @07:25PM (#609826)

        Another thing that subs have that can reveal their position is the magnetic field of their hull.

        I worked with someone many years ago who had done work on subs for the US Navy (he was very vague on exact details). "Red October" had just come out and we were talking about magnetohydrodynamic engines. He told me flat out the tech would never be used in vessels that need to be stealthy for the simple fact that the magnetic field needed for a MHD propulsion system would make the vessel *very* detectable at a surprisingly long range.

        That said this kind of tech sounds like it would be great for many other classes of vessels that do not need to be as concerned about stealth as submarines.

        --
        "Beware those who would deny you Knowledge, For in their hearts they dream themselves your Master."
    • (Score: 2) by JoeMerchant on Thursday December 14 2017, @12:51PM (2 children)

      by JoeMerchant (3937) on Thursday December 14 2017, @12:51PM (#609670)

      A caterpillar drive, but turned inside out.

      Good news for sub-chasers, the IR signature of this beast will be huge.

      --
      🌻🌻 [google.com]
      • (Score: 2) by Osamabobama on Thursday December 14 2017, @10:00PM (1 child)

        by Osamabobama (5842) on Thursday December 14 2017, @10:00PM (#609906)

        ...the IR signature of this beast will be huge.

        They will probably be able to find a way to shield the IR emissions with a thick layer of water.

        --
        Appended to the end of comments you post. Max: 120 chars.
        • (Score: 3, Informative) by JoeMerchant on Thursday December 14 2017, @11:20PM

          by JoeMerchant (3937) on Thursday December 14 2017, @11:20PM (#609973)

          Even a thick layer of water will show high magnitude anomalous heating... IR satellites are sensitive to small fractions of a degree change in temperature, and a big area with a 0.2C increase in surface - tracking in a given direction at a given speed, would be quite a giveaway.

          --
          🌻🌻 [google.com]
  • (Score: 3, Interesting) by c0lo on Thursday December 14 2017, @09:09AM (12 children)

    by c0lo (156) Subscriber Badge on Thursday December 14 2017, @09:09AM (#609626) Journal

    From TFA

    Urzhumov says that for an actual ship or submarine to ever use such a device, it would need a nuclear reactor to power it, given the enormous energy requirements to cloak an object of that size. That does not mean, however, that a smaller diesel vessel could not power a smaller cloaking device to shield potentially vulnerable protrusions from detection.

    Enormous energy requirements, eh?
    At over 1.2-or-so volts, water electrolyzed. Assuming one doesn't eliminate the same by electrolysing everything around, the 'enormous energy requirements' should come from ginormous currents.
    Yeah, right, now tell me about those ohmic losses, will you? Are they enough to heat that water around the 'tincan' you want stealthy to 'pasteurize' the content?

    --
    https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
    • (Score: 2) by c0lo on Thursday December 14 2017, @09:12AM (2 children)

      by c0lo (156) Subscriber Badge on Thursday December 14 2017, @09:12AM (#609628) Journal

      Fucking autocorrect!!!

      Assuming one doesn't eliminate the wake by electrolysing...

      --
      https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
      • (Score: 2) by MostCynical on Thursday December 14 2017, @09:20AM (1 child)

        by MostCynical (2589) on Thursday December 14 2017, @09:20AM (#609629) Journal

        Does it count if you only use your thumbs?

        --
        "I guess once you start doubting, there's no end to it." -Batou, Ghost in the Shell: Stand Alone Complex
        • (Score: 2) by c0lo on Thursday December 14 2017, @10:15AM

          by c0lo (156) Subscriber Badge on Thursday December 14 2017, @10:15AM (#609640) Journal

          Fat fingers. I'm using a stylus - equiv 1-finger typing.
          Fortunately, 2 hours/day only, while travelling.

          --
          https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
    • (Score: 3, Informative) by Anonymous Coward on Thursday December 14 2017, @10:28AM (3 children)

      by Anonymous Coward on Thursday December 14 2017, @10:28AM (#609643)

      Cloaking the electromagnetic emissions themselves seems like a bigger problem.

      • (Score: 0) by Anonymous Coward on Thursday December 14 2017, @01:19PM (1 child)

        by Anonymous Coward on Thursday December 14 2017, @01:19PM (#609675)

        I don't think EMR goes far underwater.

        • (Score: 2) by c0lo on Thursday December 14 2017, @10:35PM

          by c0lo (156) Subscriber Badge on Thursday December 14 2017, @10:35PM (#609928) Journal

          I don't think it will be much E component, they'll probably use DC to drive the water around, AC will only slosh the water.
          So rather a largish static magnetic field.

          --
          https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
      • (Score: 0) by Anonymous Coward on Thursday December 14 2017, @03:00PM

        by Anonymous Coward on Thursday December 14 2017, @03:00PM (#609697)

        the water will do that for you free of charge.

    • (Score: 2) by The Mighty Buzzard on Thursday December 14 2017, @11:31AM (2 children)

      by The Mighty Buzzard (18) Subscriber Badge <themightybuzzard@proton.me> on Thursday December 14 2017, @11:31AM (#609653) Homepage Journal

      So, not really helpful for my john boat then. And here I was all ready to get a bigger trolling motor.

      --
      My rights don't end where your fear begins.
      • (Score: 3, Interesting) by JoeMerchant on Thursday December 14 2017, @12:55PM

        by JoeMerchant (3937) on Thursday December 14 2017, @12:55PM (#609672)

        Your john boat would benefit more from passive nanomaterial coatings, a good hydrophobic should help getting on-plane faster, once on-plane all this hydrodynamics stuff is much less important. Of course, instead of mucking around with hydrophobic coatings, an extra 10hp in the motor will get you even better speed, if not efficiency - but john boats aren't much about efficiency anyway.

        --
        🌻🌻 [google.com]
      • (Score: 1, Funny) by Anonymous Coward on Thursday December 14 2017, @11:14PM

        by Anonymous Coward on Thursday December 14 2017, @11:14PM (#609965)

        Save your money. Just go to the oar house and get bigger oars.

    • (Score: 4, Interesting) by JoeMerchant on Thursday December 14 2017, @12:53PM

      by JoeMerchant (3937) on Thursday December 14 2017, @12:53PM (#609671)

      Water is a great heat sink, especially when you are moving through it at speed. Get up to 5 knots before engaging the drive - just don't think that you won't be visible to every IR satellite looking at your piece of ocean.

      --
      🌻🌻 [google.com]
    • (Score: 2) by Immerman on Thursday December 14 2017, @02:55PM

      by Immerman (3985) on Thursday December 14 2017, @02:55PM (#609696)

      Or, the enormous energies go largely to generating magnetic fields within the vehicle, so that relatively low currents in the water will generate the same thrust.

  • (Score: 0) by Anonymous Coward on Thursday December 14 2017, @01:33PM

    by Anonymous Coward on Thursday December 14 2017, @01:33PM (#609678)

    If you can seriously reduce the drag of boats, that's huge. Perhaps air planes too?

    Having said that I would like to gawk at the nekkid ladies just as much as the next guy...

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