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OfflineHagbardCeline
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Was Bernoulli wrong? The Theory of Radial Momentum.
    #5629942 - 05/14/06 08:29 PM (17 years, 8 months ago)

I began reading about Ed Seykota because his reputation as a commodities and equities trader. Considering his background as an MIT graduate who approached the market with an entirely mechanical trading system - which produced some of the biggest gains ever achieved in the markets - it isn't surprising that he would approach something with a fresh look.

I'm curious to see what some of the members here who have an obviously above average understanding of physics would have to say about this. His simple explanations and experiments do ring true, but I keep thinking I'm missing something that might cast doubt about his theory. Likewise, even more so, there was always something about Bernoulli's Principle that I didn't understand. I specifically remember questioning it (in Middle School I think).

Much more at his site.

*****************************************************************



Radial Momentum

an Up-Lifting Remedy for Bernoulli's Principle

by Ed Seykota, (c) 2001






Wing Lift

Scientists and text books incorrectly apply Bernoulli's Principle to explain lift. The drawing to the left is typical.




Spool and Card

Air flows down through the hole in a spool of thread, and a playing card adheres to the bottom of the spool. Contrary to popular belief, Bernoulli's Principle does not explain this curious phenomenon. The Theory of Radial Momentum does explain this, and many other phenomena as well.




Levitator

Levitator test disks, like the playing card, above, that allow for radial expansion of air, all adhere to the spool. Only the disk that entrains parallel flow fails to adhere. This indicates that radial expansion of air, not its velocity accounts for lift.






Tube and Cone

Air flow through a paper cone tends to collapse the cone while air flow through a paper tube has no such effect. This demonstrates that pressure relates to radial expansion of air, not to its velocity.



Radial Momentum

Laws

P = 1/3 [MR2 / mV]

P = K / r2

P = K / r




Math

Pressure equals 1/3 the square of Radial Momentum divided by the product of the mass and the volume.

For spherical expansion, pressure is inversely proportional to the square of the radius of expansion.

For planar expansion, pressure is inversely proportional the radius of expansion.



Radial Momentum in a Nut Shell

Say a bomb explodes in space. The fragments speed out, radially, in all directions so all the particles have Radial Momentum relative to the center of mass. The sum of all these individual momenta from all the fragments is the total Radial Momentum of the system.

Like linear momentum, Radial Momentum obeys conservation laws.

The particles keep expanding out into space, and the volume they occupy becomes larger and larger, so the volume density of the particles decreases, and the pressure drops. PV = NRT. Another name for pressure drop is lift.

For hundreds of years, scientists and text book writers keep trying to explain that flow-induced lift is a Bernoulli phenomenon. They claim that pressure drop is a function of the linear velocity of a stream of fluid.

This web site demonstrates with simple experiments and models, that Radial Momentum, and not linear fluid velocity accounts for pressure drop.



The Author



Ed Seykota, shown at Lake Tahoe Nevada, USA, with son, Ziz and daughter, Aziza. He has an engineering degree from MIT, specializing in servo-dynamic modeling and computer simulations using Euler's method.

http://www.seykota.com/rm/Overview.htm


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I keep it real because I think it is important that a highly esteemed individual such as myself keep it real lest they experience the dreaded spontaneous non-existance of no longer keeping it real. - Hagbard Celine


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OfflineHagbardCeline
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Re: Was Bernoulli wrong? The Theory of Radial Momentum. [Re: HagbardCeline]
    #15608028 - 01/02/12 10:35 PM (12 years, 29 days ago)

Nobody ever responded to this...


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I keep it real because I think it is important that a highly esteemed individual such as myself keep it real lest they experience the dreaded spontaneous non-existance of no longer keeping it real. - Hagbard Celine


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OfflineBambi
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Re: Was Bernoulli wrong? The Theory of Radial Momentum. [Re: HagbardCeline]
    #15608623 - 01/03/12 01:32 AM (12 years, 29 days ago)

Looks pretty interesting, maybe ill give it a better look over when im in the mood to think and not sleep.


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OfflineSeussA
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Re: Was Bernoulli wrong? The Theory of Radial Momentum. [Re: HagbardCeline]
    #15608778 - 01/03/12 03:18 AM (12 years, 29 days ago)

> This demonstrates that pressure relates to radial expansion of air, not to its velocity.

No it doesn't.  The author would need to measure the actual pressure to make such a claim.  The difference could be in the strength of the materials used to make the cone and tube or it could be related to the surface area upon which the forces act (the cone in the picture has a much larger surface area than a tube).


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InvisibleJohn NadaDiscord
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Re: Was Bernoulli wrong? The Theory of Radial Momentum. [Re: Seuss]
    #15620706 - 01/05/12 03:17 PM (12 years, 26 days ago)

I don't know anything about physics but I never really thought of pressure as correlative to velocity. This is a pretty interesting thread.


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Invisibleteknix
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Re: Was Bernoulli wrong? The Theory of Radial Momentum. [Re: John Nada]
    #15621050 - 01/05/12 04:32 PM (12 years, 26 days ago)

What if you combine ionization to the lift from the wing?

That would be pretty sweet to land at 20 knots. Charge the wing before landing and then slllloooow riiiiide, the plane on in.

G-Ridin teh aero plane.

Lacking in physics though, sry.

Could you see a 747 being out ran by a moped?

:lol:


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OfflineHagbardCeline
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Re: Was Bernoulli wrong? The Theory of Radial Momentum. [Re: Seuss]
    #15623397 - 01/06/12 12:43 AM (12 years, 26 days ago)

Yeah, I will agree that on the surface that looks pretty flimsy (pun intended) as evidence.  He apparently will answer any challenge put forth about it, and it may have already been addressed.

Having actually gone to the website again after so long and reading, he never claims Bernoulli was wrong.  Instead what I think he takes issue with is using it to explain lift, where he believes (and quotes) Bernoulli himself would agree.


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OfflineAnnom
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Re: Was Bernoulli wrong? The Theory of Radial Momentum. [Re: HagbardCeline] * 1
    #15625321 - 01/06/12 12:49 PM (12 years, 25 days ago)

Bernoulli's equation can easily be derived from Newton's F=ma, on the assumption of frictionless and incompressible flow,

Formula: 0

The last is also called the momentum equation. Integrate and you get Bernoulli's equation. A relation between pressure and velocity that stays constant along a streamline.

It's Newton applied to a fluid.

There are many explanations for lift. Some more fundamental than others. Lift, over a wing (airfoil), is mainly produced by a difference in pressure over the top and bottom of the wing. Why this pressure difference is there is basically "just" because airflow obeys Newton's laws and conservation of mass/energy. The shape of the airfoil causes a smaller cross-section for the air flowing over the wing. Conservation of mass/energy tells that the velocity thus has to go up. Newton than tells that the pressure will go down. This is not easy to imagine and not intuitive for most.

That is for lift over an airfoil. A flat plat at an angle also produces lift, but this is of a different nature.

The exact why and how lift is generated when it flows over different geometries is still open for discussion, but it's hard to argue that the flow does not follow Newton and conservation of mass/energy.


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OfflineHagbardCeline
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Re: Was Bernoulli wrong? The Theory of Radial Momentum. [Re: Seuss]
    #15625493 - 01/06/12 01:31 PM (12 years, 25 days ago)

Quote:

Seuss said:
> This demonstrates that pressure relates to radial expansion of air, not to its velocity.

No it doesn't.  The author would need to measure the actual pressure to make such a claim.  The difference could be in the strength of the materials used to make the cone and tube or it could be related to the surface area upon which the forces act (the cone in the picture has a much larger surface area than a tube).





http://www.seykota.com/rm/tube_and_cone/tube_and_cone.htm

Check that link and he shows it again, a tube and cone made from the same sheet of paper.  Same thing happens.


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I keep it real because I think it is important that a highly esteemed individual such as myself keep it real lest they experience the dreaded spontaneous non-existance of no longer keeping it real. - Hagbard Celine


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OfflineHagbardCeline
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Re: Was Bernoulli wrong? The Theory of Radial Momentum. [Re: Annom]
    #15625567 - 01/06/12 01:51 PM (12 years, 25 days ago)

Thanks for your input.  Did you visit the site?

I don't think he ever argues anything you just stated.  And as you said that "the exact why and how lift is generated when it flows over different geometries is still open for discussion", I think he is trying to explain that better.


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I keep it real because I think it is important that a highly esteemed individual such as myself keep it real lest they experience the dreaded spontaneous non-existance of no longer keeping it real. - Hagbard Celine


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OfflineAnnom
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Re: Was Bernoulli wrong? The Theory of Radial Momentum. [Re: HagbardCeline]
    #15625718 - 01/06/12 02:34 PM (12 years, 25 days ago)

Yes, I did visit the site. My post was not a direct reply to his words.
I found his reasoning a bit vague. His radial momentum may be more intuitive in the spool and card case, but not to explain lift on a wing.
There is a common misconception about how lift is generated, but I don't think he does a good job tackling that problem.


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InvisibleDieCommie

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Re: Was Bernoulli wrong? The Theory of Radial Momentum. [Re: HagbardCeline]
    #15626700 - 01/06/12 06:21 PM (12 years, 25 days ago)

I don't understand what he means by radial momentum.  I wish he posted the units it has and done some math with it...


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