colebrook_white - Colebrook-White equation

3.2.1 colebrook_white - Colebrook-White equation

f = colebrook_white(d,e,re,coeff=’normal’)

Calculate the Colebrook-White equation for a given Reynolds number $Re$ , a pipe diameter $D$ and an absolute roughness $ε$ .

( ) √︁1--=-2log --ε- + -c⎷-- f 3.7D Re f

The equation is solved numerically. If the $D$ argument is not needed it can be set to $D = 1$ . The constant $c$ nominally is $c= 2.51$ , however the American Gas Association (AGA) and the American Bureau of Mines recommend $c= 2.825$ .

Arguments

d

Pipe internal diameter ( $m$ ).

e

Pipe effective roughness $ε$ .

re

Reynolds number

coeff

Optional coefficient to use, this can be:

normal: Standard definition of $c= 2.51$ (default).
aga or abm: Definition of $c= 2.825$ .
(numeric value): Real number, user supplied.

Returns Darcy friction factor $f$ , dimensionless.

Possible Warnings

Colebrook-White formula is for turbulent flow Re > 4000: The Colebrook-White equation is normally for turbulent flow.

Possible Errors

Colebrook-white vectors must be of same size: Multiple arguments are specified as vectors whose number of elements don’t match.
Colebrook-White unknown coefficient string type: The given coeff argument is not numeric, but also not one of normal, abm or aga.

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