The Cole Siphon

[Guest Aemilius]

Hey Moontanman....

 

Maybe you're right, maybe I misunderstood you, sorry if that's the case. You've asked me what I'm getting at here and I'm afraid I just can't be any clearer than what I wrote in that last post. Since CraigD is a Science Instructor, and C1ay is a Hydraulic Systems Specialist, maybe we should wait for them to chime in on this.... What do you say? Anyway again, in a nutshell....

 

What I'm saying is that (hypothetically) a strong magnetic field in close proximity to the surface of the diamagnetically enhanced fluid in the resevoir may enable continued flow by taking advantage of the diamagnetic property of the fluid tending to create a depression in the surface of the diamagnetic fluid in the resevoir that permits the tube on the left to terminate at a lower level than the level at which the other end of the tube on the right emerges from the surface of the diamagnetic fluid it's immersed in while both continue to be exposed to the same level/degree of atmospheric pressure.... satisfying the conditions required for the normal operation of a siphon.

 

What do I have to do.... draw you a picture? Just kidding around man.... take it easy.

Edited June 29, 2013 by Aemilius

[Guest Aemilius]

I'm just thinking here Moontanman.... Can you use one of the many illustrations here to point me to the area of concern? Just an idea, if you see one that illustrates/exemplifies what you have in mind. Feel free to modify it (the diagram) any way you please, maybe add an arrow to show what direction you think I intend the fluid to flow in. Oh yeah, I just noticed you're still using the word "suction".... It's atmospheric pressure, not suction.

Edited June 29, 2013 by Aemilius

[CraigD]

THE COLE SIPHON.... A hypothetical closed system wherein an inverted U shaped tube formed of two legs of unequal length can transfer fluid from a higher level to a lower level within a single resevoir over an intermediate elevation by the pressure of the atmosphere in forcing the fluid up the shorter branch of the tube immersed in it while the excess of weight of the fluid in the longer branch when once filled causes a continuous flow.

 

Aemilius - a couple of questions:

 

By “the longer branch”, do you mean the left part of the tube, or the right?

 

Do you mean that the tube on the left stops before the depressed surface of the flud?

[Guest Aemilius]

Hey CraigD....

 

CraigD "By 'the longer branch', do you mean the left part of the tube, or the right?"

 

The longer branch is considered to be on the left (in the diagram you reproduced).

 

CraigD "Do you mean that the tube on the left stops before the depressed surface of the flud?"

 

Yes, I mean that the tube on the left (shown in the diagram as already being filled with fluid at the moment the thought experiment begins) terminates just above the depressed surface of the fluid leaving an air gap.

 

A more concise rephrasing of the text accompanying the diagram you reproduced might be....

 

"....that (hypothetically) a strong magnetic field in close proximity to the surface of the diamagnetically enhanced fluid in the resevoir may enable continued flow by taking advantage of the diamagnetic property of the fluid tending to create a depression in the surface of the diamagnetic fluid in the resevoir that permits the tube on the left to terminate at a lower level than the level at which the other end of the tube on the right emerges from the surface of the diamagnetic fluid it's immersed in while both continue to be exposed to the same level/degree of atmospheric pressure.... satisfying the conditions required for the normal operation of a siphon."

 

Didn't know if you'd seen that earlier post.

Edited June 29, 2013 by Aemilius

[CraigD]

OK, since the end of the left tube is lower than where the right tube enters the water, per the simplified, approximate hydrostatic pressure equation, there will be pressure difference,

 

[math]P = h p g[/math]

 

where [imath]h[/imath] is the height difference, [imath]p[/imath] the density of the fluid and [imath]g[/imath] the acceleration of gravity.

 

So fluid will flow from the right end of the tube to the left end. Because the tube is higher in places than the water surface, this is called a siphon. As long as there’s a height difference, there will continue to be pressure, and right-to-left flow.

 

This is also true if the left side of the tube enters the fluid in the place where its surface is lower than where the right tube does. Since pressure is proportional to height difference, it’s best to do this - the “air gap” won’t make the syphon stop, but it won’t flow as fast with one without an air gap.

 

It’s not a perpetual motion machine, because, no matter how it’s done – magnetics, a downward air jet, a simple dam between the left and right sides of reservoir, etc. – mechanical work must be done to keep the surface of the water near the left end of the tube lower than near the right end. It won’t stay in that condition without work, because the siphon increases the volume of water on the left side, and thus, increase its height. This work could be done by a motor driving some sort of pump, including something exotic like the “magnetic dimple maker” scheme Aemilius sketched and described above, or, if the left and right sides of the reservoir are sufficiently dammed from one another, a drain to keep the left surface always lower than the right.

[Guest Aemilius]

Thank you for that CraigD.... I understand. I'll just ruminate on what you've written here for a little while before responding.

Edited June 29, 2013 by Aemilius

[Turtle]

Now I'll begin exploring/describing how the behaviour of the fluid in the system might be affected using magnetism. ...snip

 

an externally applied magnetic field. In this situation, as the fluid falls downward into the resevoir under the force of gravity, its advance will be diamagnetically resisted as it enters the externally applied magnetic field from above, and it's retreat will be diamagnetically aided as it exits the externally applied magnetic field below on it's way to the resevoir with a net gain of zero in either upward or downward force. ...snip

 

I believe the fluid may impart a torque on the magnet which will of necessity generate heat, which is a loss. I'm presuming here that force is as force does and that if a magnet is acting on a diamagnet, then the diamagnet is acting on the magnet in an opposite & equal fashion. I find only a description of the torque on a magnet by another magnetic field and extrapolating that to diamagnetism. ?

 

 

Magnets

...

 

A magnet both produces its own magnetic field and responds to magnetic fields. The strength of the magnetic field it produces is at any given point proportional to the magnitude of its magnetic moment. In addition, when the magnet is put into an external magnetic field, produced by a different source, it is subject to a torque tending to orient the magnetic moment parallel to the field.^[9] The amount of this torque is proportional both to the magnetic moment and the external field. A magnet may also be subject to a force driving it in one direction or another, according to the positions and orientations of the magnet and source. If the field is uniform in space, the magnet is subject to no net force, although it is subject to a torque.^[10]

 

I also think that the specific shape of the reservoir dimple may affect any actual operation of the theoretical siphon, and it's certainly an interesting theoretical question. Consider that any depression must match the shape of a ring magnet's field. Perhaps the dimple is too deep and not wide enough to clear an air gap? :smart:

 

Is the dimple rimpled by the field lines? :wave:

 

I think the specifcs of the apparatus must of needs be described, such as the diameter & thickness of the tube and the density of the fluid. :shrug:

 

Dipole Magnetic Field Of Ring Magnet

 

 

 

Edited June 29, 2013 by Turtle

[C1ay]

Below is depicted a straight tube closed at one end and open at the other (already filled with fluid). The lower open end of the tube terminates beneath the surface of the fluid in the resevoir and the upper end is closed, preventing normal atmospheric pressure from acting on it. In this situation nothing will happen.... the fluid level within the tube will not rise or fall. Gravity acting on the fluid is uniform (in the tube and the resevoir) and normal atmospheric pressure coming to bear on the surface of the fluid in the resevoir will exert pressure at the base of the water column created by the tube, keeping the water from just falling into the resevoir (as it would in a vacuum). The fluid will remain at rest within the tube. The sum of all the equal and opposite forces acting on the system will be zero.... static equilibrium.

 

 

This system would actually function as a barometer if you marked some graduations on the tube so you could see the water level move up and down which changes in atmospheric pressure :o

[Guest Aemilius]

Hey CraigD....

 

CraigD "So fluid will flow from the right end of the tube to the left end. Because the tube is higher in places than the water surface, this is called a siphon. As long as there’s a height difference, there will continue to be pressure, and right-to-left flow."

 

 

I hope you don't mind me pressing you on this CraigD, but I really do need to be clear.... Are you saying (hypothetically) that in the diagram above, you believe that due to the height difference between the two columns of fluid interacting with a single resevoir, that the fluid should not only begin to flow but that it should continue to flow until the installed enabling permanent magnet is no longer strong enough to cause/maintain the needed depression on the surface of the resevoir? That could be a very, very long time couldn't it?

 

CraigD "This is also true if the left side of the tube enters the fluid in the place where its surface is lower than where the right tube does. Since pressure is proportional to height difference, it’s best to do this - the “air gap” won’t make the syphon stop, but it won’t flow as fast with one without an air gap.

 

Actually, that air gap is crucial and was intentionally engineered into the system. If we were discussing a conventional arrangement, similar to the siphons Moontanman uses for example, I would agree with you completely about both ends being immersed.... However, if I'm not mistaken (open to correction), the magnetic field acting on the surface of the resevoir, by repelling the fluid downward, will be exerting a force on it equal to the force of the volume of fluid that would be there if no magnetic field was applied. Therefore, the fluid pressure existing at/just beneath the surface of the fluid at the bottom of the depression should be found to be the same as if there were no depression at all. That being the case, immersing the left end of the tube in the resevoir at the bottom of the depression would expose it to fluid pressure equal to the pressure that would exist there if there were no depression. The sum of all the forces acting on the system would then be zero.... static equilibrium.

 

CraigD ".... mechanical work must be done to keep the surface of the water near the left end of the tube lower than near the right end. It won’t stay in that condition without work, because the siphon increases the volume of water on the left side, and thus, increase its height."

 

Right, work must be done. But it seems to me this case could be a bit differrent, since the rate at which the fluid enters the resevoir on the left would be matched precisely by the rate at which the fluid exits the resevoir on the right, so the fluid level in the resevoir as a whole would remain constant. In other words.... As the tube on the left begins and then continues to flow into the resevoir on the left fluid pressure will rise in that region, but by the same token, as the fluid begins and then continues to be forced up the tube from the resevoir on the right by atmospheric pressure the fluid pressure in that region will fall. As it is atmospheric pressure that does the work of forcing fluid through the siphon tube, so would it also be atmospheric pressure that does the work of equalizing the fluid pressure in the resevoir as a whole by forcing the fluid entering the resevoir on the left that would tend to increase the pressure in that region towards the right where the fluid being forced up the tube by atmospheric pressure would tend to decrease the pressure in that region.

 

Thanks again for responding.

Edited July 1, 2013 by Aemilius

[C1ay]

What I'm saying is that (hypothetically) a strong magnetic field in close proximity to the surface of the diamagnetically enhanced fluid in the resevoir may enable continued flow by taking advantage of the diamagnetic property of the fluid tending to create a depression in the surface of the diamagnetic fluid in the resevoir that permits the tube on the left to terminate at a lower level than the level at which the other end of the tube on the right emerges from the surface of the diamagnetic fluid it's immersed in while both continue to be exposed to the same level/degree of atmospheric pressure.... satisfying the conditions required for the normal operation of a siphon.

Assuming that there is in fact a depression in the resevoir that is caused by a magnetic repulsive force on the fluid in the resevoir then I think the same magnetic repulsive force will oppose the gravitational force on the diamagnetic fluid inside the tube above the magnet as well thereby preventing continuous flow.

[Guest Aemilius]

C1ay "Assuming that there is in fact a depression in the resevoir that is caused by a magnetic repulsive force on the fluid in the resevoir...."

 

There are no assumptions required concerning the diamagnetic effect that will arise as a result of the magnet's close proximity to the surface of the fluid in the resevoir.

 

C1ay "....then I think the same magnetic repulsive force will oppose the gravitational force on the diamagnetic fluid inside the tube above the magnet as well thereby preventing continuous flow.

 

Please see posts 4, 6 and 7.

Edited July 1, 2013 by Aemilius

[C1ay]

Please see posts 4, 6 and 7.

In my opinion the assumptions in those posts do not take into account things like capillary action and/or the associated cohesive and adhesive forces that are variables in the system with a magnitude dependent on the materials used. Additionally it appears also that there is an assumption that the magnetic force and the gravitation force are balanced to some extent which would only be the case for a very specific quantity of fluid in the tube at some very specific strength of magnetic field. How sensitive is the system to the balance of forces? Is it more like balancing a brick on its end or more like standing a razor blade on its edge?

 

Consider one example. Using the image depicted in post 4, is there a tube size and a suitably sized magnet for a given combination of materials where the fluid in the tube above the magnet would be levitated and the net effect of the magnet would not be zero?

 

BTW, to what extent does viscosity of the fluid in the system affect the other forces at play?

[Guest Aemilius]

C1ay "In my opinion the assumptions in those posts do not take into account things like capillary action and/or the associated cohesive and adhesive forces that are variables in the system with a magnitude dependent on the materials used.

 

Of course, you're welcome to your opinion C1ay, but capillary action has more to do with "....the drawing up of liquids between the hairs of a paint-brush, in a thin tube, in porous materials such as paper, in some non-porous materials such as liquified carbon fiber, or in a cell." - Wikipedia. That means your opinion of it as being any kind of significant contributing factor in this scenario simply becomes a negligible non-issue for the purpose of this discussion (both now and in the future) by assigning a diameter of 1.5 inches to the siphon tube.

 

C1ay "Additionally it appears also that there is an assumption that the magnetic force and the gravitation force are balanced to some extent which would only be the case for a very specific quantity of fluid in the tube at some very specific strength of magnetic field."

 

Would it be asking too much of you to provide a quote or a clearly marked reproduction of one of the diagrams indicating any of that?

 

C1ay "How sensitive is the system to the balance of forces?"

 

Is there some particular reason you think this siphon should be any more or less sensitve to the balance of forces than any other siphon? If so, explain.

 

C1ay "Is it more like balancing a brick on its end or more like standing a razor blade on its edge?"

 

No C1ay, it's really more like.... a siphon.

 

C1ay "Consider one example. Using the image depicted in post 4, is there a tube size and a suitably sized magnet for a given combination of materials where the fluid in the tube above the magnet would be levitated and the net effect of the magnet would not be zero?"

 

 

I contend that as the fluid falls downward into the resevoir under the force of gravity in the diagram you refer to from post 4 (through a 1.5 inch diameter tube), its advance will be diamagnetically resisted as it enters the externally applied magnetic field from above, and it's retreat will be diamagnetically aided as it exits the externally applied magnetic field below on it's way to the resevoir with a net gain of zero in either upward or downward force. To suggest that perhaps there may be a possibility that one pole of the magnet could exert a greater upward force on the fluid immediately above it than the downward force that the other pole would exert on the fluid immediately below it would mean that the magnet would have to have a greater field strength at one end than the other, an absurd proposition.

 

C1ay "BTW, to what extent does viscosity of the fluid in the system affect the other forces at play?"

 

My impression is you think somehow that in this arrangement the fluid will mysteriously behave differently than the fluid would in a "normal" siphon. There's no reason to expect that a given degree of viscosity of the fluid in this system should affect the forces at play to any greater or lesser extent than they would be expected to affect the forces at play in the system of any other siphon of the same dimensions employing a fluid of comparable viscosity.

Edited July 2, 2013 by Aemilius

[Guest Aemilius]

Hey CraigD....

 

CraigD "....mechanical work must be done to keep the surface of the water near the left end of the tube lower than near the right end. It won’t stay in that condition without work, because the siphon increases the volume of water on the left side, and thus, increase its height."

 

I just wanted to revisit this because I think I see a contradiction....

 

CraigD "This work could be done by a motor driving some sort of pump, including something exotic like the “magnetic dimple maker” scheme Aemilius sketched and described above...."

 

It would at least seem here that you've lumped together a permanent magnet and a powered pump requiring constant input of energy (electric, gas, hydraulic, etc.) in the same sentence and declared them both to be capable of doing work on the system in the same way. Did you mean to do that? A force must move an object to do work on it right? For example, my refrigerator magnet's force isn't moving anything, and it does no work on anything. By the same token, the magnet causing the depression on the surface of the diamagnetic fluid in the resevoir doesn't move anything, and it does no work on anything. When it comes to the fluid within the tube no work is being done by the magnet either, a point that's already been exhaustively explored in the series of foundatonal example diagrams I posted (particularly posts 4, 6 and 7 ) leading me to finally conclude that ...."No imposition of any externally applied magnetic field anywhere along the length of the siphon in this scenario will result in any tendency on the part of the diamagnetic fluid within the tube to move in one direction or the other, whether the fluid be at rest or in motion." So, as I see it, the magnet can't do any work on the fluid within the tube by moving it, and it can't do any work on the fluid in the resevoir by moving it either. Where in any of this do you see the magnet as doing work on the system? I know you're busy so I won't bog you down with any more posts until you get a chance to comment on this post and the last post I wrote you.

Edited July 2, 2013 by Aemilius

[C1ay]

C1ay "In my opinion the assumptions in those posts do not take into account things like capillary action and/or the associated cohesive and adhesive forces that are variables in the system with a magnitude dependent on the materials used.

 

Of course, you're welcome to your opinion C1ay, but capillary action has more to do with "....the drawing up of liquids between the hairs of a paint-brush, in a thin tube, in porous materials such as paper, in some non-porous materials such as liquified carbon fiber, or in a cell." - Wikipedia. That means your opinion of it as being any kind of significant contributing factor in this scenario simply becomes a negligible non-issue for the purpose of this discussion (both now and in the future) by assigning a diameter of 1.5 inches to the siphon tube.

I guess we'll handle this one step at a time since you think this is of so little impact on your thought experiment. Try this experiment in real life, not in your head. Take a very thin vessel like a capped off straw, fill it with water and invert it. You will notice the water stays in the straw. This happens because the surface tension caused by the adhesive force with the container and the cohesive force of the water molecules to themselves is stronger than the air pressure outside the container so the air does not bubble up through the liquid to the vacuum at the top allowing it to run out of the container. Now try this with something 1.5 inches in diameter like a small glass and you will notice the water runs out freely. If you now try this with more viscous fluids like honey you will see that you can increase the diameter of the container larger than a straw and still get the liquid to maintain a vacuum in the top of the container that doesn't allow the air to bubble up through it. With fluids as viscous as axle grease you can increase the container size to several inches in diameter.

 

BTW, I am not only entitled to my opinion I am also entitled here to tell you that your experiment is not valid just because you say so. You cannot just dismiss challenges by saying what is a significant factor or not without showing some math and science to support it. Show us now just exactly how much levitating force is resultant from your magnet and how little the adhesive and/or cohesive forces come into play based on the viscosity of your fluid and the dimensions and material of the tube. I know from real life experience that I cannot invert a container of water with an opening on 1.5 inches and expect the water to stay in the container. It doesn't even happen with a simple soda bottle with a 3/4" opening. Now trying showing us some actual physics instead of just word play. We'll move on to your other assertions after you've show some scientific support for this one.

[Guest Aemilius]

I'm sorry C1ay, right now I'm really only interested in CraigD's response to posts

26 and 31. Please feel free though to continue posting and discussing the issues

you've raised with other members that share your concerns.

Edited July 2, 2013 by Aemilius

[Guest Aemilius]

Never mind all that about posts 26 and 31 CraigD. I think I've got it now.... I'll just go ahead and assert here that the only force needed to do work on this system is gravity in response to an imbalance within the siphon tube that causes a potential difference to exist between the respective weights of the two columns. The magnet can't do work on the system to maintain the depression, but it can act on the system to maintain the depression. In other words.... The depression on the surface of the fluid is simply the diamagnetic fluid's reaction to the static magnetic field.... not work.

 

Gravity is the only force needed to do work on this system

 

 

So now it's down to one last question.... Am I correct in my assertion or can you (or anyone) verifiably show why some other force or input of energy (mechanical or otherwise) would need to do work on this system in order for the siphon to continuously circulate the fluid? This has been a fantastic brain teaser.... Thanks man!

Edited July 5, 2013 by Aemilius