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Relation between Serghides friction factor and Moody diagram

  1. Jun 11, 2010 #1
    Hi All,
    I'm working on some fluid modeling, and I'm calculating my friction factor using Serghides' method, which, I'm sure you all know, is very accurate in relation to the Colebrook equation. The trouble is, I need to convince my boss that the Serghides equation has merit and is that accurate. When we were talking about it, he said to make a Moody diagram using Serghides' equation to prove to him that the lines were correct. I've got relatively limited software, just Excel right now, and I'm sure that I could plot a diagram as a function of relative roughness and Reynolds number that would yield the friction factor, but it looks to me like it needs to be in terms of f and Re yielding the relative roughness. Is that the case, and is there a method that I could use within Excel to plot the Moody diagram, or would I need something like MatLAB? Thanks.

    Nevermind. Got it.
    Last edited: Jun 11, 2010
  2. jcsd
  3. Jun 21, 2010 #2
    I'm trying to do the exact same... how did you "get it" with Excel?
  4. Jun 22, 2010 #3
    What I did was basically setting up a table with the Reynolds numbers in rows and the relative roughness numbers in columns. Go to the first column in your data sheet, then go down one cell and write your first Reynolds number and continue going down the column writing your range of Re. Then, go to the first cell in the second column and write your first relative roughness number and compute the friction factors in the rest of the cells in the second column. Move to the next column, write your second relative roughness number, compute friction factors, and so on until you have used your range of relative roughness numbers. I used ranges of Re from 2 x 10^3 to 1 x 10^8 and relative roughness from 1 x 10^-6 to 5 x 10^-2. By taking relatively small steps after each increase in decimal place in the Re numbers, the curve looks a little more smooth. Good luck!

  5. Jun 22, 2010 #4
    Thanks, James! I'll get right on it.


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