[ExI] underwater sprinkler, was: RE: Musical instruments in space

[John Clark]

On Sun, Mar 31, 2013 at 12:50 AM, spike <spike at rainier66.com> wrote:

> Consider an S-shaped sprinkler suspended from a latex hose, underwater.
> Imagine water is pumped thru the sprinkler in the traditional manner at 1
> ml per second, and we discover the sprinkler rotates positive pi radians.
> 2 ml per second rotates it 2 pi radians and so on.****
>
> Now imagine pumping water thru it backwards.
>

Blowing and sucking are not symmetrical processes, that's why it's easy to
tell if a film of a sprinkler is running forward or backward and why you
can blow water as high as you want but no matter how powerful the pump is
on the surface of the earth you can only suck water about 25 feet. In one
case a pump is increasing pressure inside the narrow sprinkler nozzle
causing the water to move in just one direction, perpendicular to the
nozzle opening. But in the other case when the pump is decreasing pressure
inside the small nozzle the water moves inside because of the outside
pressure produced by the weight of the water and the air on top of it, and
that pressure is coming from all directions so the water is coming through
the opening from all directions too, and so no narrow beam of water is
formed and no net torque is produced.

  John K Clark





>   For any steady flow, we observe zero rotation.  If the flow is
> accelerated backwards at 1 ml per second squared, what is the rotation?  If
> the flow is 2 ml per second squared, do we get twice the rotation?  If we
> use a denser fluid, does it require the same flow acceleration to produce a
> rotation?  Or less?  Or more?  Could we use a compressible fluid like air
> and get similar results?  Does the shape of the nozzles come into play?
> There is a lot of science in that simple experimental setup.  ****
>
> ** **
>
> Truth: we don’t **really** understand a system until we can derive a
> system of simultaneous differential equations that can correctly model its
> behavior.****
>
> ** **
>
> spike****
>
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>
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