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The difference between system equili and system and steady state

  1. Apr 28, 2003 #1


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    Can anyone explain the difference between a system at equilibrium and a system at steady-state water flow?

    I know that equilibrium occurs at equal rates, no net change is produced. But I don't understand steady state system....Please explain it to me.... Thanks

    also the difference between saturated and unsaturated hydraulic conductivity? I have hard time to understand these stuffs.. If anyone know these stuffs, can u please explain it to me. Thanks.
  2. jcsd
  3. May 5, 2003 #2

    Tom Mattson

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    I'm moving this to Physics, where perhaps it will get some discussion.
  4. May 5, 2003 #3
    Equilibrium: dU/dx = 0 (usually this happens at extrema of potential energy).
  5. May 6, 2003 #4

    Tom Mattson

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    OK, at first I thought you meant the "zero force" condition, but now I am thinking that you are referring to the continuity equation. That is because when you say "equal rates", it makes me think of "equal flow rates into and out of a volume".

    So, that statement of equilibrium would be:


    I dug up the old Fluid Mechanics book (it's been about 10 years!) and looked up the mathematical definition of steady state. It is...


    for any fluid property A. That would include the density ρ, which reduces the continuity equation to:


    This I don't know. Our local "fluids" guy is Enigma; try sending him a PM.

    edit: fixed ∂ signs.
  6. May 6, 2003 #5
    I would call steady state a state at which power (rate of chande of energy dU/dt) is constant.
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