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Method & Apparatus For Collapsing Water Waves AKA the Bubble Wall Breakwater

Home Forums Archive Structure Designs Method & Apparatus For Collapsing Water Waves AKA the Bubble Wall Breakwater

This topic contains 12 replies, has 6 voices, and was last updated by Avatar of admiral-doty admiral-doty 4 years, 1 month ago.

Viewing 13 posts - 1 through 13 (of 13 total)
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  • #1211
    Avatar of Altaica
    Altaica
    Participant

    Popular Science (1943)

    “Air Bubbles Employed To Form Breakwater”

    A new type of breakwater consisting of nothing more than air bubbles recently was devices for quieting even the highest waves of the sea. It is the invention of Phillip Brasher, an American. One of the units is said to have been operated successfully at El Segundo, CA, to protect a concrete pier.

    The air breakwater consists of a perforated pipe that is laid along the sea bottom and connected with a land air-compressing station. In rough weather it is merely necessary to allow the compressed air to escape from the holes in the pipe, the air bubbles quickly rising to the surface. The wall of bubbles is said to break up the waves and retard their forward motion. When the water from a broken wave flows back to form a base for the next incoming wave, it finds no support and the next wave curls over and breaks.

    The repetition of this process is said to result in a smooth surface beyond the pipeline, no matter how rough the weather. A simple installation of the pipe system, the inventor says, is sufficient to provide a harbor of smooth water in exposed points around coasts that have caused trouble in the past

    US patent 2325937

    #9748
    Avatar of CrosiarCM
    CrosiarCM
    Participant

    Wow, great find Altaica,

    So the questions I have are:

    • How much air are we talking?
    • How much energy would it take to generate that amount of air?
    • How big a wave can it break?
    • Can it break a rogue wave?

    I know you probably can’t answer any of these, but this is the first I have heard of any t ype of technology that could act as a breakwater on the open sea.

    – You may get what you want, but will you want what you get?

    #9756
    Avatar of xns
    xns
    Participant

    I can understand the theory and it’s very clever… though the scale of this must be absolutely massive! You’re basically using air bubbles to remove kinetic energy from the water before it hits the seastead. At the same time you’re attempting to reduce the density of the water(and air) above the pipeline to the point that it can no longer support the wave.

    Once again, this is brilliant! But it must be absolutely MASSIVE.

    King Shannon of the Constitutional Monarchy of Logos.

    #9758
    Avatar of Altaica
    Altaica
    Participant

    xnsdvd wrote:
    You’re basically using air bubbles to remove kinetic energy from the water before it hits the seastead. At the same time you’re attempting to reduce the density of the water(and air) above the pipeline to the point that it can no longer support the wave.

    I think your a bit confused. Waves don’t move water, waves more THROUGH water. this imparts the energy of the wave into the bubbles.

    I think it’s a combination of the waves being reflected back and the bubbles being pushed out of the water.

    Hopefully it’s the how thick the wall of bubbles is and the percentage of the volume that’s air and not the size of the individual bubbles.

    Οὐκ ἐμεῦ ἀλλὰ τοῦ λόγου ἀκούσαντας ὁμολογέειν σοφόν ἐ&si

    #9759
    Avatar of J.L.-Frusha
    J.L.-Frusha
    Participant

    Until it’s been fully examined, it boils down to opinions, as to how it works. My thoughts are that the bubbles add energy to the water, moving the curtain in an upward direction, countering the leading-edge of the rotational force of the waves rotary motion, causing it to collapse.

    Later,

    J.L..F.

    If you can’t swim with the big fish, stick to the reef

    #9761
    Avatar of Melllvar
    Melllvar
    Participant

    Funny, I remember this idea being suggested on these boards somewhere and not being taken seriously. (Edit: Well, I thought I did, but now I can’t seem to find the thread, so nevermind…)

    I too am curious what the cost of operating the system is… fortunately it would only need to function part time (when the waves get bad). I’m even more curious as to the relationship between wave amplitude and length, amount of air mixed and the percentage of energy removed. Viewing it as wave dampening due to fluid density/viscosity change, its hard to guess whether there is a certain threshold density below which no wave higher than a certain amplitude could sustain itself(and would therefore break, hopefully long before the seastead), or whether the amount of energy removed is simply a continuous function of wave size and air/water ratio.

    Either way, there’s potential energy savings… if a threshold density/amplitude, then at least you don’t have to spend more energy to break bigger waves, and if not, then at least you don’t have to spend excessive energy to break the small waves.

    #9763
    Avatar of xns
    xns
    Participant

    Actually… now that I think of it, we see similar phenomenon occurring when we drive into the wake of a large vessel. There’s a patch of very flat sea where the water is still being pushed up by the propeller. Perhaps Frusha’s right and the bubbles serve a similar purpose, as well as removing the forward kinetic energy.

    King Shannon of the Constitutional Monarchy of Logos.

    #9765
    Avatar of Altaica
    Altaica
    Participant

    Melllvar wrote:
    I too am curious what the cost of operating the system is… fortunately it would only need to function part time (when the waves get bad).

    Do you really want to be driving a boat around your seastead in bad weather?

    Οὐκ ἐμεῦ ἀλλὰ τοῦ λόγου ἀκούσαντας ὁμολογέειν σοφόν ἐ&si

    #9767
    Avatar of Melllvar
    Melllvar
    Participant

    The OP was talking about a laid pipe that released air bubbles to retard wave motion. My comment was that it would only need to operate during bad sea conditions, when the waves needed to be reduced. Where does driving a boat around come in?

    Also, noticed that the patent was dated 1943… so I’m guessing this idea probably didn’t pan out after all, or else one of the breakwater companies would have picked it up by now. But its worth keeping in mind.

    #9770
    Avatar of admiral-doty
    admiral-doty
    Participant

    The bubbles change the wave propagation properties of the water. They do not actually absorb all of the energy from the waves. The air/water mixture can be viewed as a composite which has different mechanical properties than pure water/sea water. It is similar in concept to changing the properties of solid materials by filling, alloying or doping the main element with small amounts material.

    Air is compressible while water is hydraulic (incompressible). The speed of sound is also different in air and water. The air bubbles make the air/water mixture somewhat compressible and reduce the efficiency of the wave propagation through the water. A change in speed of wave propagation through the water results in destructive interference between the slowed down wave in the aerated patch and the faster wave coming in behind it, greatly reducing the amplitude. Thus, a small amount of compressed air can leverage into a large impact on wave propagation. It would be interesting to experiment with using an array of compressed air emitters to channel waves into controlled areas of destructive and constructive interference, a kind of holographic wave control.

    There was a documentary on disappearing ships where one of the theories was that a sudden release of bubbling gas from the ocean floor reduce the bouyancy of the ship above when the bubble reached the surface and created a gas/water mixture, sinking the ship. It showed a model ship actually sinking in a wave tank in an experiment with compressed air.

    #9790
    Avatar of Altaica
    Altaica
    Participant

    admiral wrote:
    There was a documentary on disappearing ships where one of the theories was that a sudden release of bubbling gas from the ocean floor reduce the bouyancy of the ship above when the bubble reached the surface and created a gas/water mixture, sinking the ship. It showed a model ship actually sinking in a wave tank in an experiment with compressed air.

    Are you sure they were using AIR? I’ve only heard of them doing the experiment with Methane.

    Οὐκ ἐμεῦ ἀλλὰ τοῦ λόγου ἀκούσαντας ὁμολογέειν σοφόν ἐ&si

    #9792
    Avatar of Altaica
    Altaica
    Participant

    Melllvar wrote:

    The OP was talking about a laid pipe that released air bubbles to retard wave motion. My comment was that it would only need to operate during bad sea conditions, when the waves needed to be reduced. Where does driving a boat around come in? Go read the patent.

    Melllvar wrote:
    Also, noticed that the patent was dated 1943… so I’m guessing this idea probably didn’t pan out after all, or else one of the breakwater companies would have picked it up by now. But its worth keeping in mind.

    The patent isn’t for a laid pererated pipe on the ocien floor but for a intacted pipe that is draged by a ship.

    Letsing say that you have one bubble emiter every foot then a 0.2 kilometer breakwater would need a compressor with 656 times the copacity as the boat mounted version.

    It problily had problems working in shallow water. that and the fact you need huge compresser or a complicated system to tune the emiters on and off in turn is the most likely resone you don’t see laid pipe bubblewalls. But since we wil be out in 100 feet plus depth waters anyways it shouldn’t be a proble developing a floating bubble wall.

    Οὐκ ἐμεῦ ἀλλὰ τοῦ λόγου ἀκούσαντας ὁμολογέειν σοφόν ἐ&si

    #9796
    Avatar of admiral-doty
    admiral-doty
    Participant

    A recent paper (2009) on experiments with air bubbles in a tank with a model ship showed a loss of bouyancy only in a confined area:

    http://physics.princeton.edu/~mcdonald/examples/fluids/hueschen_ajp_78_139_10.pdf

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