# Moody's f (friction factor)

1. ## Moody's f (friction factor)

Hi guys,

I have found an excel worksheet with the following formula:
Moody's f = 0.001375*(1+(20000*Pipe Roughness factor 'k'/(Pipe Diameter)+1000000/Reynolds)^(1/3))

I haven't been able to find the reference to the formula.
I want to replace it with a formula that I can get a reference too, however every formula I have found is recursive (or requires reading off charts), I would like to find a formula that isnt recursive like the one above.

Thanks!

2. ## Re: Moody's f (friction factor)

The formula you showed is not recursive. Can you be more specific about the issue? Can you provide the Excel worksheet you are talking about?

What do you mean by a reference? Do you mean a source that provides and explains a formula? I was able to find this: https://www.sciencedirect.com/topics...riction-factor The references to Moody seem to more along the lines of a type of graph rather than a scalar factor.

Your question is a pretty esoteric engineering question rather than an Excel question, so you may have better luck on engineering forums.

3. ## Re: Moody's f (friction factor)

Originally Posted by 6StringJazzer
The formula you showed is not recursive. Can you be more specific about the issue? Can you provide the Excel worksheet you are talking about?

What do you mean by a reference? Do you mean a source that provides and explains a formula? I was able to find this: https://www.sciencedirect.com/topics...riction-factor The references to Moody seem to more along the lines of a type of graph rather than a scalar factor.

Your question is a pretty esoteric engineering question rather than an Excel question, so you may have better luck on engineering forums.
The formula you showed is not recursive.
yes, but it does not provide a source or reference. I would like to use a formula that is also not recursive, but with a reference.

4. ## Re: Moody's f (friction factor)

I would like to use a formula that is also not recursive, but with a reference.
I don't know that any of us here know fluid dynamics well enough to tell you which equation (and what the reference will be for that equation) that calculates friction losses in a pipe and is not recursive. My internet search mostly found the Darcy-Weisbach equation, and that one, like yours, is also recursive.

I know there are many engineering calculations that are recursive and there is no good way around the need for recursion. If you are certain that a non-recursive equation exists, you are more knowledgeable than we are and more likely to be able to find that equation. Once you know the equation, then you can bring it back here and we can help you program that into Excel.

If it helps, I found this tutorial specific to putting the Darcy Weisbach into Excel (complete with equations for Moody's friction factor): https://www.cedengineering.com/userf...th%20Excel.pdf

Also if it helps, I have a tutorial here that talks about programming iterative/recursive equations into Excel: https://www.excelforum.com/tips-and-...ind-roots.html

5. ## Re: Moody's f (friction factor)

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