Desperate Call To Planet Earth

Abhi, this hamster has been considering a thought exercise that might shed some light on your experiment.

At the far end of your pipe install a shutoff valve. Assume that the pipe and valve don’t burst or deform under pressure. Assume there is no friction or viscosity and no temperature changes. The experiment is reduced to a single 1-dimensional flow problem. Assume the pipe is totally filled and water is flowing from the outlet.

Now shut the outlet valve. The water in the pipe acts as a piston greatly increasing the pressure and compressing the water near the outlet. As the water is compressed under the enormous pressure the signal velocity increases. Pressure waves in the more compressed water overtake pressure waves traveling in less compressed water. This creates a shock front moving from the outlet toward the inflow. How fast will this shock front move?

Assume the average compression of the water in the compressed region is 0.001. Assume that the water is flowing at 10 mps. Then the shock front should move at 10,000 mps. Far faster that the normal speed of sound through water. That explains how the backpressure signal may travel so quickly.

Now again consider the flowing water before the valve was shut. Each gallon of water has kinetic energy that was supplied by the input pumping station. Divert the outlet flow up a ramp 100 meters high. As the increased pressure at the outlet slows the water near the outlet some of that kinetic energy will provide the energy to lift water up the 100 meters. So instead of getting something from nothing the energy supplied by the input pump to accelerate the water acts at the outlet end to lift water 100 meters. The water starts off flowing from the outlet at close to 10 mps and gradually slows to a stop. (Some of the water’s kinetic energy is stored temporarily in pressurized water. As the compressed water eventually expands there will even be a backflow at the inlet.)

That’s what this hampster guesses is happening in your experiment. Basically you were correct that signaling from the outlet to the inlet needed to occur faster than the speed of sound in unpressurized water.

 

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Thanks for your support. I request you to understand fundamental concept of my experiment i.e if there is "time interval" for information transfer, we can use it to create "free" PE. Whatever may be speed, even greater than speed of light. Basically, I am trying to prove that information transfer does not take place through pressure waves. There is another property of matter i.e. gravity.

I think only some reference from history about experimental verification can satisfy me. I am really desperate for it and unfortunately no one is telling me in any forum.

Thank you very much.

 

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Abhi, good luck on your hunt for a real world experiment. This hamster agrees that ultimately experiments and not theory determine what really happens.

This hamster hopes that while exploring information transfer at exceedingly high speeds you keep an open mind to mundane explanations. Even if you disagree with them you’ll need to understand the arguments of others before countering them with your own. In particular this hamster suggests looking closely at “information transfer does not take place through pressure waves”. There are assumptions in that statement that need close examination. Basic pressure wave analysis does not include shock waves. Velocity calculations using standard pressure wave analysis fail when the coefficients “blow-up”. Could lead in interesting directions if you choose to follow that path.

Have fun and you are welcome.

 

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The formula below appears nowhere in the experiments. It is the basic formula that is not only under scrutiny, but is essential in the calculations. Why is it not present anywhere in the experiment? I know why, but I've already stated the reasons. And there are other formulae required to continue the experiment.

v = the square root of B/p where v is the speed of sound, B is the bulk modulus of elasticity of the medium which is the extent to which increasing pressure within the medium decreases its volume, and p is the density of the medium. For example:

v = the square root of 2.2*10^9 N/m^2 (elastic property ) divided by 1000kg/m^3 (inertial property [p])

= 1483 m/s which is the speed of sound in water. A difference in the the change of temperature will result in a minor change in speed. The higher the temperature, the higher the speed.

Think about what other properties are being affected. Does the water compress? What levels of density will appear as one goes from one end of the pipe to the other at any given time? Will the density affect the speed? How? What about friction? Viscosity? Salinity?

 

Q, your last post is the kind of help that Abhi needed on the PhysicsFORUM site and did not receive.

The formula for sound velocity you’ve given likely comes from a second order wave equation for the fluid velocity. That second order equation was likely derived from two first order partial differential equations representing conservation of fluid mass and momentum. This hamster believes the transformation from those first order equations to the second order equation assumes a nearly constant bulk modulus function. In the extreme scenario of Abhi’s experiment that assumption may fail so the second order wave equation no longer models the experiment. That is why this hamster suggested that Abhi look into a shock wave solution.

This hamster agrees with your other comments. This is a difficult experiment to model realistically. That is why this hamster found Abhi’s experiment interesting.

Seems that Q and the hamster have now switched positions. Q is giving Abhi more help than this hamster was willing to provide. Hehe. Sorry. Couldn't resist.

 

Hampster

The formula for sound velocity you’ve given likely comes from a second order wave equation for the fluid velocity. That second order equation was likely derived from two first order partial differential equations representing conservation of fluid mass and momentum. This hamster believes the transformation from those first order equations to the second order equation assumes a nearly constant bulk modulus function.

Nope. The equation simply determines the speed of sound through a medium. Gas, liquid or solid. The equation is critical to his experiment. And it is an equation our astute friend is attempting to denounce. Are you beginning to see the flaw here?

That is why this hamster suggested that Abhi look into a shock wave solution.

Perhaps. A shock wave that has accelerated past its barrier wave front becomes a shock cone, or bow wave. The wave has a leading edge and a trailing edge. When the leading edge moves down the pipe it raises equilibrium pressure rapidly (compression), followed by a rapid drop in pressure (rarefaction), followed by a return to equilibrium. I would suspect that in such a closed system the wave would dissipate. Multiple waves would cancel each other out as they overtook one another.

Abhi has not taken into account the huge volume of water moving through the pipe. Speed and momentum must also be included. I suspect the composition of the pipe is infinitely strong and will hold as the water's bounding motion is suddenly stopped. The flaws are beginning to pile up.

Seems that Q and the hamster have now switched positions. Q is giving Abhi more help than this hamster was willing to provide.

Maybe I'm getting soft. However, Abhi did get the boot from the other forum. And it would appear that not many others here are coming forward to offer their insight into Abhi's thought experiments.

This briefly explains 37 different anomalies of water: http://www.sbu.ac.uk/water/anmlies.html