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Homework Help: Flow Velocity- Guranteed to be Laminar

  1. Oct 10, 2012 #1
    1. The problem statement, all variables and given/known data

    Q) Water (p = 998 kg/m^3
    , n = 1.0*10^-3 Pa.s at 20C) at 20C flows through a pipe of
    diameter 50.0 mm. What is the maximum average flow velocity if the flow is
    guaranteed to be laminar? Give your answer in mm/s.

    2. Relevant equations

    Reynolds number=(pvd)/n

    3. The attempt at a solution
    I am absolutely stumped on this last question for my assignment, I have no idea what to or how to calculate the flow from just these given constants.
  2. jcsd
  3. Oct 10, 2012 #2
    Last edited by a moderator: May 6, 2017
  4. Oct 10, 2012 #3
    You're given everything you need for the equation, except for the "soft" values Reynolds numbers that are a result of laminar flow. Most agree on the following:

    for circular pipe flow only

    laminar: Re < 2000
    transitional: 2000 < Re < 4000
    turbulent: Re > 4000

    So, pick a Re that you think will "guarantee" laminar flow, plug n chug.

    Hope I didn't just give it away too easily, but the values of Re were the only thing that you were missing.
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