Talk:Hydraulic analogy

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[edit] Lack of References

There are no references on the page. I am an amauteur user but even I can see this must be addressed

[edit] Goal

This site says: "Many writers eventually resort to some kind of water analogy to try to explain how electricity works. I have yet to see what I thought was a really good water analogy. If you want to explain electricity, talk about electricity. Hydraulics is another field entirely. Avoid this trap; it is already full."

Although I agree that most such analogies are done poorly, the potential exists for a perfectly accurate one, as they are both fluids flowing down conduits. I hope to make a page for the wikipedia that collects these ideas together into a coherent whole that the naysayers and nitpickers can then edit to perfection. - Omegatron

So I had this in my user space until it evolved into something vaguely encyclopedic, and then merged it with the pre-existing article which was just a table of related equations. Now that it is in the main article space it should evolve a lot faster. - Omegatron 02:48, July 12, 2005 (UTC)

Already I can see problems because the links are taken from websites that don't appear to be credible. If anything, they appear to be the incoherent jibberings of clueless amateurs. Take for example how pressure is equated with voltage. I'm afraid this doesn't make sense to me since pressure is what moves the liquid and so would be better equated with the electrical field since this moves charge. Secondly, unlike pressure, there is no such thing as voltage existing at a point. Voltage measures the energy gained or lost when charge moves between points and so is always referenced to two points. If you want a hydraulic analogy of voltage, then this will have to be equivalent to the energy lost or gained when a certain volume of water is transferred between two points. i.e. the change in (KE + PE). —Preceding unsigned comment added by 80.47.114.136 (talk • contribs)

[edit] Cdang's version

  • it helps a lot understanding the difference between potential and voltage:
    • potential → altitude, or pressure;
    • voltage → difference in height between the top and the bottom of the water circuit (height of the water column), or difference of pressure between upstream and downstream;
  • parallel components can be compared with communicating vessels (same voltage~same difference of pressure) and with a flow derivation (Kirchhoff's current law);
    What do you mean by "communicating vessels"? - Omegatron
  • resistance can be compared with friction (loss of charge, pressure drop):
    • resistance of the wire → friction in the pipe;
    • resistor → sinuous pipe such as heat exchanger;
  • load of an active component (e.g. charging accumulator, motor, electrolysis) can be compared with a watermill or a turbine;
    • back electromotive force → force used to make the turbine turn.

[edit] Unfinished

Moving some things here so that I can turn this into a real article:

Transformer 
like an AC piston that moves back and forth, connected externally to another such piston by a lever with a pivot in the middle. the amount of lever on each end determines the ratio, and it can only transfer AC. (of course DC at that point in the circuit would change something? hmm... [No, it only works with AC, since a transformer pretty much works by one "inductor" affecting another]). This is similar to a hydraulic transformer. A "fluid coupling transmission"?

I hope to make a better version of this

A CMOS inverter

Of course a transformer works with DC. Check out this flyback DC-DC converter. That's pure DC running through the transformer.
I.e., a transformer hydraulic analogy isn't that complex. It's basically two water turbines (inductors) connected by different-sized gears. The two water pipe systems are isolated, but when one turbine spins, it forces the other to spin at a ratio determined by the gears. -Dragonchild (12.27.39.105 (talk) 15:53, 28 November 2007 (UTC))
That analogy would work if a transformer could induce a constant DC output on its secondary if given a constant DC input on the primary. The various examples given here show the most basic operation, but they all leave out a critical step or in the general operation of a transformer. Here's how I would do it:
Image:Isolated AC-only Fluid Transducer (transformer) TEST.png
  • Start with a simple cylinder with a thin "plate" piston in it.
  • Place a spring on each side between the piston and the facing cylinder wall, so that the piston's natural position is centered along the cylinder's length.
  • Connect a pipe to each end of the cylinder. As fluid pushes the piston from one end, fluid should be pushed out the other end.
  • Connect a bidirectional delay valve to a tee on each of the two pipes. "AC" current would move the piston around, but a constant "DC" current would force the valve to open and thus mostly bypassing the piston.
  • Attach a push rod to the piston and pass it out of the assembly, through a sealed hole.
  • Now, construct a second such apparatus, perhaps with a different-sized piston/cylinder.
  • Securely fasten the two assemblies to a base so that the push rods point at each other, and fasten the two push rods together.
The amount of delay in each bypass valve together with the size of the piston basically determine the resonant frequency of each side, while the relationship between the sizes of the two pistons of course determines the ratio of the transformer as a whole.Vanessaezekowitz (talk) 10:13, 26 March 2008 (UTC)

[edit] Original talk page

I have started this article independently.  :-) They will be folded together when it is ready. See User:Omegatron/water analogy - Omegatron 21:42, May 24, 2005 (UTC)

Should this be renamed Hydraulic analogy to electric circuits? - Omegatron 21:42, May 24, 2005 (UTC)

Oh I see there is a heat analogy, too. Hmmm... - Omegatron 21:46, May 24, 2005 (UTC)

I look forward to seeing this article made more complete. The heat analogy is very important historically and I think it should remain in the article and linked to Caloric theory. That being said, I think the analogy for heat is less perfect--I don't know of a thermal equivalent of a transistor, for instance, so it makes sense to me to go into more detail with the hydraulic-electric pair. --Scentoni 06:32, 25 May 2005 (UTC)

So, the heat analogy intuitively replaces an invisible form of energy with. . . another invisible form of energy? If there's historical significance let's put it in there for completeness' sake, but I've never heard of someone successfully explaining electrodynamics in terms of heat. Personally, I found thermodynamics HARDER to understand than electrodynamics. -Dragonchild (12.27.39.105 (talk) 15:58, 28 November 2007 (UTC))
Hmmm... maybe keep the article name "Hydraulic analogy", and have a section for electrical analogy and a small section for heat analogy at the end? - Omegatron 13:50, May 25, 2005 (UTC)

[edit] Botched merge

So I attempted to merge my userfied version with the actual version, but accidentally moved the talk page over top of the article instead of the talk page, undeleted the old history before I realized it, blah blah etc. Anyway, the end result is that some of the original article's history is now in the talk page history. Sorry. All the info's still there, but it is for the wrong page. - Omegatron 02:42, July 12, 2005 (UTC)

[edit] Rectilinear transformer

http://virtual.cvut.cz/dynlab/courseModeling/node42.html


[edit] Failures of the model

I've added a section about the limits of the analogy. (Useful analogies can lead to serious misconceptions when we don't know when to drop them, and instead use a better model.)

[edit] 2D would be clearer

although the 3d images are nice, 2d would be much clearer. —Preceding unsigned comment added by Laplacian (talk • contribs) 02:03, 13 May 2008 (UTC)

[edit] Inductors

Might it be better to describe inductance as a turbine instead, or in addition to, a paddle wheel? It seems easier to visualize a turbine as part of a closed hydraulic system as opposed to a paddle wheel, which really only works in a hydraulic analogy that includes gravity. —Preceding unsigned comment added by 128.118.147.10 (talk) 20:26, 30 May 2008 (UTC)