Relation between Serghides friction factor and Moody diagram

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Discussion Overview

The discussion centers around the use of Serghides' friction factor method in fluid modeling and its comparison to the Moody diagram. Participants explore how to effectively plot the Moody diagram using Serghides' equation, particularly in the context of limited software capabilities.

Discussion Character

  • Technical explanation
  • Homework-related

Main Points Raised

  • One participant expresses the need to demonstrate the accuracy of Serghides' method compared to the Colebrook equation and seeks guidance on plotting the Moody diagram using Excel.
  • Another participant requests clarification on how to implement the plotting process in Excel after the first participant indicates they figured it out.
  • A detailed method is provided by a participant, describing how to set up a table with Reynolds numbers and relative roughness to compute friction factors, including specific ranges for Reynolds numbers and relative roughness.

Areas of Agreement / Disagreement

Participants appear to share a common interest in using Serghides' method and plotting the Moody diagram, but there is no explicit consensus on the best approach or the accuracy of the method itself.

Contextual Notes

Participants discuss the limitations of using Excel for plotting and the potential need for more advanced software like MATLAB, indicating that the method's effectiveness may depend on the tools available.

Who May Find This Useful

This discussion may be useful for individuals working on fluid dynamics modeling, particularly those interested in comparing different methods for calculating friction factors and plotting related diagrams.

jp8weaver
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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:
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I'm trying to do the exact same... how did you "get it" with Excel?
 
desiree74 said:
I'm trying to do the exact same... how did you "get it" with Excel?

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!

James
 
Thanks, James! I'll get right on it.

cheers,

Desirée
 

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