Pipeline Toolbox
Function Reference Manual
Early Public Release DD-00011-000

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 f =-2log ( ε 3.7D+ c 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.