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Homework Help: Fluid Mechanis - Pipe Flow Velocity

  1. Sep 20, 2009 #1
    1. The problem statement, all variables and given/known data
    I'm looking for a formula that has velocity at a certain point in a pipe. I only have velocity and pipe diameter.

    The problem goes something like:

    A Tube with a 0.075 meter diameter has four drains equally spaced apart
    with a cap at the far end. Each of the four drain opening has a flow of
    15 L/s.

    I need to find the average Vs in the tube between each of the drains, I marked them as 1, 2, and 3. If the flow is laminar, what are the max velocities at 1, 2, and 3? List assumptions needed for solving.


    2. Relevant equations
    I'm still missing a relevant formula...

    3. The attempt at a solution
    To start of I think that three boundary systems would need to be used:
    System 1:
    Drain 1
    Location 1

    System 2:
    Drain 2
    Location 2

    System 3:
    Drain 3
    Location 3
    Drain 4
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Sep 20, 2009 #2
    I worked on the problem a bit more:

    I found the pipe area

    A= 0.785 * Diameter2

    and Q or liquid flow rate = Rho * V * Area

    so in order for the first velocity at the drain to be 15l/s, the Q must be at least 66.27 l/s

    I'm still pretty stuck though and not sure if I'm going in the right direction
  4. Sep 22, 2009 #3
    to find the entrance flow rate you have to do continuity, so pVa=4(pVa)
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