6 ms·
When I watch things floating in water, objects below the water seem to move back and forth with the movement of the water, as if the object and the water were t
by Declanomous 9y ago
When I watch things floating in water, objects below the water seem to move back and forth with the movement of the water, as if the object and the water were the same, but things that are partially in the water, they seem to "ride" the water and shift much more slowly.
Based on that, my guess is either surface tension, or the fact that an object that floats on top of a medium is much less dense than one that floats within it. It would probably be a pretty easy to quantify if you had several liquids with known surface tension, so I'm guessing the information is out there already.
- cr1895 9y agoHere's a gif of water particle movement that's happening in an ocean wave (in deep water; it gets weirder if it's shallow). http://funnel.sfsu.edu/courses/gm309/images/Owave.gif http://funnel.sfsu.edu/courses/gm309/images/Owave.gif Essentially, motion starts with wind. Energy propagates downwards into the water column resulting in the circular orbitals (you see this if you float in the (deep) ocean and you bob up and down in a circle but you don't really go anywhere). But at a certain point, no more energy propagates downward; so your submarine if its deep enough (tens of meters) will not feel a thing from what's happening on the surface. This is also what the FLIP takes advantage of; the base of its deep spar hull lies so far below the surface that it has nothing forcing it to move up and down. This is why it's stable in big waves, and why I'm confused how a submarine is too unstable.
- jononor 9y agoI'd expect a stationary submarine to be much more suceptible to rolling? A raised tower or other non-symmetrical features might also cause a bobbing motion in the roll. I'd also expect the submarine to have to adjust its ballast tanks in order to maintain a level buoyancy. When a submarine is moving at cruise speed these things can easily be compensated for by the fins and rudders, but the motors will neccesarily make noise. Heck, even moving through the water (instead of floating with the current) may create undesirable artifacts.
- cr1895 9y agoYeah could be prone to high roll motion depending on the heading relative to the predominant waves. I'm guessing though that for whatever scientific purposes it would be submerged and not rolling/pitching at all.
- amelius 9y agoIn that case wouldn't a set of gyroscopes and/or gimbal solve the problem in a cheaper way?
- cr1895 9y agoSolve what problem? If you make something gimbaled on a ship (pool table, for instance) you can prevent rotation, but not translation...at least not without some complicated active motion compensation system.