Fanning Friction Factor

  1. Maylis

    Maylis 842
    Gold Member

    Hello,

    I was wondering if when calculating the fanning friction factor, do english units need to be used?

    The equation for the head friction is

    h_f = 4f(L/D)V^2/2

    where L is the length, D is the diameter of the pipe, and f is the fanning friction factor. This ends up having units of length squared/time squared, but I think it should be power/mass
     
  2. jcsd
  3. SteamKing

    SteamKing 9,125
    Staff Emeritus
    Science Advisor
    Homework Helper

    I don't know about your dimensional analysis. The Fanning friction factor is non-dimensional.

    http://en.wikipedia.org/wiki/Fanning_friction_factor

    BTW, your formula for head loss due to friction is incorrect. It should be:

    h_f = 4f(L/D)V^2/(2g)
     
  4. Maylis

    Maylis 842
    Gold Member

    Is the g included whether you use english units or not? I get confused when I need to divide by g or not these days since we keep going back and forth with english and SI units
     
  5. SteamKing

    SteamKing 9,125
    Staff Emeritus
    Science Advisor
    Homework Helper

    Yes, the g is always there, even in SI or furlongs per fortnight units. Do a dimensional analysis and confirm.
     
  6. Maylis

    Maylis 842
    Gold Member

    You can see why I was confused, this is directly and repeatedly on the lecture slides
     

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