Can We Break the Underwater Barrier Like the Sound Barrier?

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    Barrier Underwater
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Discussion Overview

The discussion explores the concept of whether an underwater barrier, analogous to the sound barrier in air, can be broken by an object moving faster than sound in water. Participants examine the implications of such a phenomenon, including the formation of shock waves and cavitation effects.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions if an object can move faster than the speed of water molecules and what the consequences would be.
  • Another participant suggests that a water shock wave would form at the bow of the object and notes that sonar would be ineffective due to the speed of the object exceeding that of sound in water.
  • A different viewpoint clarifies that moving "faster than sound" refers to surpassing the speed of sound waves, not the movement of water molecules.
  • It is mentioned that while the speed of sound is greater in water than in air, no conventional boat or torpedo reaches this speed, though supercavitating torpedoes can achieve significant speeds through cavitation.
  • One participant asserts that supercavitating torpedoes do indeed move faster than sound in water by creating a bubble of air around them, effectively allowing them to travel through a medium that is not water.
  • A later reply acknowledges the previous correction about the torpedoes, noting that they do not actually exceed the speed of sound in water but rather travel within a bubble of air.

Areas of Agreement / Disagreement

Participants express differing views on the nature of the underwater barrier and the mechanics of supercavitating torpedoes. There is no consensus on whether an underwater barrier analogous to the sound barrier exists or the specifics of how supercavitating torpedoes operate.

Contextual Notes

Participants discuss various definitions of speed and the implications of moving through different mediums, but there are unresolved assumptions regarding the mechanics of sound and cavitation in water.

oozie1
[SOLVED] Underwater barrier

[?] Since I've been lookin a the concept and knowledge to what happens when the sound barrier gets broken and how it happens, it got me thinking about if the same thing can happen in water.
i.e. If an object was to move faster than the water molecues could move what would happen?
An if anything at all would it be physically possible.

----------OOZIE--------------------
 
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You would get a water shock wave forming at the bow of the object. Sonar wouldn't work (the sound would be going slower than the object).
You'd also get huge cavitation: localized drop in pressure would cause air to bubble out of the water (I don't know the technical term for the phenomena).

Do a search for 'supercavitating torpedos' for a real life example of this. Cool Stuff.
 
A couple of points: moving "faster than sound" means moving faster than a sound wave. It has nothing to do with "moving faster than water molecules".


The speed of sound increases as density of the medium increases so the speed of sound is greater in water than it is in air. At the same time, it is harder for a physical object to move through a denser medium. No boat or torpedo goes anywhere near the speed of sound. Propellors spinning rapidly can: that's where you get "super cavitation".
 
Actually, the supercavitating "torpedos" do move faster than sound in water, afaik.

They are shaped in such a way that a bubble of air cavitates around it, and it effectively turns into an underwater missile.

EDIT: You're right though, Ivy. Those "torpedos" (which are still in development) don't actually go faster than sound in water. They form a bubble of *not water* which they are going fast in.
 
Last edited:
[?] thanks for that and to the person above the post above.
I saw that definition of speed of sound. an i thought that the sound barrier is when an object moves faster than air particles can move. I was just asking if a similar effect happened in water i wasnt saying they were related!
Thanks both
-----------------------------OOZIE-----------------------
 

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