Swamee & Jain Friction Factor Equation
Swamee & Jain Friction Factor Equation
(OP)
Hello,
The original Swamee & Jain explicit equation for friction factor calculation for turbulent flow in pipes has f = 0.25/[(log.....)]^2.
I have also seen on the web f = 1.325/[(log.....)]^2. The difference is NOT the factor of four beween the Fanning friction factor and the Darcy friction factor. Can anyone explain the discrepancy?
Thanks
The original Swamee & Jain explicit equation for friction factor calculation for turbulent flow in pipes has f = 0.25/[(log.....)]^2.
I have also seen on the web f = 1.325/[(log.....)]^2. The difference is NOT the factor of four beween the Fanning friction factor and the Darcy friction factor. Can anyone explain the discrepancy?
Thanks
RE: Swamee & Jain Friction Factor Equation
never seen the 1.325, but the 0.25 is the one I memorised after checking it against Shacham and Colebrook White with good correlation.
I expect it may be a mistake.
If you are from Perth Australia, you probably got Swamee Jain 0.25 from the Hardie Iplex PE manual. Where did the 1.325 come from?
Cheers
Steve McKenzie
RE: Swamee & Jain Friction Factor Equation
Id est,
Thus, one formula is based on log x, and the other on ln x.
Would I be right ?
RE: Swamee & Jain Friction Factor Equation
Yes, you're correct - I have gone back and checked the two articles using 1.325 in the formula and they DO use ln rather than log. Thanks for spotting the difference.
RE: Swamee & Jain Friction Factor Equation
Regards,
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RE: Swamee & Jain Friction Factor Equation
"Things should be made as simple as possible, but not any simpler." Albert Einstein