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Fluid mechanics - Poiseuille Equation

  1. May 3, 2007 #1
    The question is as follows:

    Determine the maximum velocity at which the poiseuille Equation may be used for
    a) water flowing in pipes diameter 0.001m, 0.015m & 0.20m, stating f, pressure drop/length in each case.
    b) Re-work question a) using air instead of water.

    I am a bit confused as to how i reach the maximum velocity in each lengths of pipe any help would be greatly appriciated guys.

    thank you in advance.
  2. jcsd
  3. May 4, 2007 #2


    User Avatar

    Staff: Mentor

    Think in terms of transition from laminar to turbulent flow - Poiseuille's law (or the Hagen-Poiseuille law) is valid for laminar flow. The maximum velocity is that velocity (or speed) where the flow begins transition from laminar to turbulent.
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