Coriolis(sp?) Effect
John Bottoms
I was having a discussion with a performing artist about an upcoming project.
The centerpiece of the project is the duplication of a fountain that shoots
550' into the air. In the past it has been impossible to get this altitude
because the coriolis effect would cause the water stream to breakup before
reaching that altitude. In fact, there seems to be an impenetrable barrier
at between 320-370'.
The pump is an off the shelf item. The secret ingredient is the nozzle. He
(the artist) declined to answer questions about the construction so I didn't
press for further details. It seems he is under a non-disclosure agreement on
the construction. Is this a well known problem and what are the theories on
dealing with it.
-johnbottoms
Concord, MA
SCOTT I CHASE
It's not the Coriolis force which breaks up the stream. It's the turbulence
in the flow. The nozzle you refer to is a device which produces laminar
flow by forcing the water through a series of long straw-like tubes,
followed by some fine mesh (and maybe some other processing is involved -
I never learned all the details) in order to smooth out the flow.
So far as I know this pump is made by only one company, whose founder
developed it as a PhD project in Mech. E., and has since gone into the
fountain business. His computer-controlled pumps can produce surprising
displays of "jumping" water and other such things which can't be done
with water straight from the tap.
-Scott
-------------------- i hate you, you hate me
Scott I. Chase let's all go and kill barney
SIC...@CSA2.LBL.GOV and a shot rang out and barney hit the floor,
no more purple dinosaur.
Andrew Poutiatine
Did your friend tell you that Coriolis is to blame for the breakup of the
jet? If this is what I think it is, namely a fountain shooting a jet of water
vertically into the air, then Coriolis has _nothing_ to do with it, even if
the emerging jet has some rotational component to its velocity about
the axis of the jet. Now, if the jet is located on some
revolving mechanism, and has some radial component to
its outcoming stream, then Coriolis may indeed be important.
Certainly the effects of the Earth's rotation, and the associated Coriolis
effects are absolutely negligibel compared to gravitational and inertial
effects in the jet. So, unless the fountain is some complex hydro-mechanical
thingy, then the Coriolis line is just BS.
About the break up of the jet, the nozzle is a _very_ important influence.
The surface tension effects are one of the real killers, and reducing surface
tension would help, but you probably can't reduce it enough to see too much
of a difference. Besides, adding a surfactant to the water would probably
cause more harm than good, since it would foam. The other real killer is
the turbulence, both within the emerging jet, and in the shear layer
surrounding the jet as it travels through the air. One would like a nice
laminar flow to emerge from the jet, since any turbulence will introduce
instabilities that will both allow the surface tension effects to come into
play sooner, and enhance the shear layer turbulence surrounding the jet.
A lot of work goes on these days on water jets as applicable to cutting. In
these systems, it is important often to keep the jet coherent as long as
possible, so that you can cut deeper into the material. One approach has been
to introduce turbulence suppressing polymers into the fluid. A friend of
mine from MIT (Saurov Bhunia) was working on this problem a few years back.
He also experimented with density and viscosity (using mixtures of water and
glycerine).
I don't know how much if any of this has been applied to
fountains, since usually they are an artistic rather than a scientific
endeavor. I haven't really heard of any research concerning bigger fountains
also perhaps because it smacks of penis envy or some kind of size complex.
(No offence to those out there obsessed with big fountains :^) ).
The bottom line is that the nozzle will influence the coherence of the jet
to a large degree by influencing turbulence both within and without the
jet, and it is very likely that a novel nozzle is being employed. I also think
that there are other important methods that should/may be considered here,
like the polymer concept. Coriolis is most likely a misused term in this case.
Lastly, I don't know why anyone would want to conceal their fountain
technology. Are there high tech fountain spies out there selling the
Japanese our innovative fountain secrets? Wierder things have happened,
haven't they? I mean I can't think of any, but hey.
I hope this helps.
-AIP
Dylan Norhtup (PHY)
incompatibilities of the two prevailing theories. Aren't the two just
based on different mathematical systems (linear algebra and matrix
mechanics)? I have been told that they can both prove the same things.
So the big question is: Why are they incompatible?
No flames, please, because I reaad my news with my finger on the ^N button!
*****************************************************************************
* Witty Remark * Dylan Northrup <nort...@chuma.cas.usf.edu> * This space *
* Here * a.k.a. Doc X & Vinx<vi...@illuminati.io.com * for rent *
*****************************************************************************
Stephen Collyer
|> I know this may seem a little obtuse of me but I don't see teh
|> incompatibilities of the two prevailing theories. Aren't the two just
|> based on different mathematical systems (linear algebra and matrix
|> mechanics)? I have been told that they can both prove the same things.
|> So the big question is: Why are they incompatible?
I expect you'll get the real answer from John Baez, but the most obvious
incompatibility that I can think of is this:
QM has uncertainty principles, and GR doesn't.
The problem is that uncertainty principles do appear to make useful predictions
in the real world, and as in principle, a GR calculation can violate an
uncertainty principle, you've got a clash.
Steve Collyer.
Ludwig Plutonium
nort...@chuma.ec.usf.edu. (Dylan Norhtup (PHY)) writes:
> I know this may seem a little obtuse of me but I don't see teh
> incompatibilities of the two prevailing theories.
Dylan notice that the Coulomb law has the very same math form as the
law of gravity, only the Coulomb is exponentially more stronger. All of
physics is quantum physics and GR is just a weak form of the Coulomb
interaction.
So many intuitionless professors of physics try to reconcile QM to
GR. But in every test match between QM and GR, QM has always won-- Bell
inequality and Aspect experimental results.
The importance should be the other way around for GR is just closet
attic space in the universe of physics-- one atom of Pu.
NOVICE, CHURCH OF APPLIANTOLOGY
I have a question which goes along with this.
If the force carrier in quantized gravity is a graviton how would the graviton
get out of a black hole to affect nearby masses?
Joe Dellwo
Rob Douglas
In article <29SEP199...@stc06.ornl.gov>, del...@stc06.ornl.gov (NOVICE, CHURCH OF APPLIANTOLOGY) writes:
|> In article <28a6vn$d...@suntan.eng.usf.edu>, nort...@chuma.ec.usf.edu. (Dylan Norhtup (PHY)) writes...
|> >I know this may seem a little obtuse of me but I don't see teh
|> >incompatibilities of the two prevailing theories. Aren't the two just
|> >based on different mathematical systems (linear algebra and matrix
|> >mechanics)? I have been told that they can both prove the same things.
|> >So the big question is: Why are they incompatible?
|> >
|>
|> If the force carrier in quantized gravity is a graviton how would the graviton
|> get out of a black hole to affect nearby masses?
Well, why would a graviton be attracted to strong masses.
If it were, then the force of gravity would drop off as the sqare of r
times the mass, since higher masses would slow down/de-energize the
gravitons. Since this doesn't happen, gravitons cannot be affected by
gravity. So it gets out of the black hole.
ROB
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Disclaimer-type-thingie>>>>> These opinions are mine! Unless of course
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But with my intellect, I doubt it. Besides, if it was useful
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john baez
>In article <28a6vn$d...@suntan.eng.usf.edu>, nort...@chuma.ec.usf.edu. (Dylan Norhtup (PHY)) writes:
>|> I know this may seem a little obtuse of me but I don't see teh
>|> incompatibilities of the two prevailing theories. Aren't the two just
>|> based on different mathematical systems (linear algebra and matrix
>|> mechanics)? I have been told that they can both prove the same things.
>|> So the big question is: Why are they incompatible?
>
Well, maybe *a* real answer...
First of all, general relativity is not based on linear algebra, at
least not in at all the same way as quantum theory is. Second of all,
they don't prove the same things or even treat the same subjects!
Quantum theory is a general framework for dealing with physics of all
sorts; every force has a quantum mechanical description so far except
gravity. General relativity, on the other hand, is a theory PRIMARILY
of gravity.
As for why gravity seems so hard to fit into the quantum-mechanical
framework, this is one of the themes of my series called "This Week's
Finds in Mathematical Physics" on sci.physics.research. I think I gave
one of the main reasons in "week19". It may be more advanced than the original
questioner wanted, but he should feel free to say "huh?" (though more
specific questions would be better).
The quantum field theories that describe three of the forces of nature
(electromagnetic, strong and weak) depend for their formulation on a
fixed metric on spacetime - that is, a way of measuring distance and
time. Indeed, it seems pretty close to being true that spacetime is
R^4, and that the "interval" between any two points in 4-dimensional
space is given by the Minkowski metric
dt^2 - dx^2 - dy^2 - dz^2
where dt is the change in the time, or t, coordinate, dx is the change
in the spatial x coordinate, and so on. However, it's apparently not
quite true. In fact, the presence of matter or energy distorts this
metric a little, and the effect of the resulting "curvature of
spacetime" is perceived as gravity. This is the basic idea of general
relativity, which is nicely illustrated by the way in which the presence
of the sun bends starlight that passes nearby.
Gravity is thus quite different from the other forces, at least to our
limited understanding. The other forces we have quantum theories of,
and these theories depend on a *fixed* (that is, pre-given) metric.
We have no quantum theory of gravity yet, only a classical theory,
and this theory is precisely a set of equations describing a *variable*
metric, that is, one dependent upon the state of the universe. These
are, of course, Einstein's equations.
In fact it is no coincidence that we have no quantum theory of gravity.
For most of the last 50 years or so physicists have been working very
hard at inventing and understanding quantum field theories that rely for
their formulation on a fixed metric. Indeed, physicists spent huge
amounts of effort trying to make a theory of quantum gravity along
essentially these lines! This is what one calls "perturbative" quantum
gravity. Here one says, "Well, we know the metric isn't quite the
Minkowski metric, but it's awfully close, so we'll write it as the
Minksowski metric plus a small perturbation, derive equations for this
perturbation from Einstein's equations, and make a quantum field theory
based on *those* equations." That way we could use the good old
Minkowski metric as a "background metric" and thus use all the methods
that work for other quantum field theories. This was awfully fishy
from the standpoint of *elegance*, but if it had worked it might have
been a very good thing, and indeed we learned a lot from its failure to
work. Mainly, though, we learned that we need to bite the bullet and
figure out how to do quantum field theory without any background metric.
Gregory Weeks
At the heart of any quantum mechanical theory is a (noncommuting)
algebra of observables. But, for reasons I won't go into, GR lacks
easily described observables and has no local observables at all.
So there is a real problem.
People have tried to ignore the problem by considering nonobservables
with vague connections to reality. In this case, it turns out that
the infinities encountered in the construction of the interacting field
theory can't be renormalized away.
So there is a deep theoretical problem and a shallow practical problem.
Greg Weeks
Archimedes Plutonium
However, I believe this is required when you see New Ohm's law as being V = CBE rather than V = CR. I have seen analogies to toll booths on highways to try to ease the discomfort of this counterintuitive. But a better explanation is that Old Physics Ohm's law V = CR is just plain wrong. When we include Resistance = Magnetic field X Electric field the parallel circuit with added resistors making overall resistance go down is now easily explained.
AP, King of Science, especially Physics
Archimedes Plutonium
It is clear from observing the indicator bulbs in the above diagrams that the addition of more resistors causes the indicator bulb to get brighter. For parallel circuits, as the number of resistors increases, the overall current also increases. This increase in current is consistent with a decrease in overall resistance. Adding more resistors in a separate branch has the unexpected result of decreasing the overall resistance!
(snipped)
The Tollbooth Analogy
The effect of adding resistors is quite different if added in parallel compared to adding them in series. Adding more resistors in series means that there is more overall resistance; yet adding more resistors in parallel means that there is less overall resistance. The fact that one can add more resistors in parallel and produce less resistance is quite bothersome to many. An analogy may help to clarify the reason behind this initially bothersome truth.
--- end quoting from the Web ---
AP does not like counterintuitiveness in science. So whenever counterintuitive rears its ugly head, means there is probably something wrong in theory. And no analogy is going to rectify the problem.
So it is my hunch that the "Decrease in overall resistance" is because Old Physics Ohm's law has V= CR when it really is V = CBE.
But it is late at night and will work on this tomorrow....
