Fanning Friction Factor for Smooth and Rough Pipes
This Demonstration plots the Fanning friction factor versus the Reynolds number, , for both rough and smooth pipes.[more]
The Fanning friction factor is given by the following relationships:
(i) For a laminar regime (,
(ii) for a turbulent regime in smooth pipes (,
(iii) for a turbulent regime in rough pipes (,
where is the roughness ratio. The light green shaded region corresponds to the laminar/turbulent transition regime where experimental results are unreliable.
Side note: an explicit version of the Colebrook–White equation derived by Shacham (see )
gives equivalent results.[less]
 J. O. Wilkes, Fluid Mechanics for Chemical Engineers, Upper Saddle River, NJ: Prentice Hall, 1999.