The Darcy-Weisbach head loss equation is formulated as follows:
where:
H = head loss (m or ft) in pipe
L = length of pipe (m or ft)
d = diameter of pipe (m or ft)
Q = flow rate in the pipe (m3/s or cfs)
g = gravitational acceleration (9,81 m/s2 or 32,2 ft/s2)
f = Darcy-Weisbach pipe friction coefficient
The Darcy-Weisbach friction factor f can be calculated with the Colebrook-White equation, for pipes with turbulent flow:
In Wadiso, the user specifies an absolute roughness k, in which case the f is dependent on Re and is calculated with the appropriate equation.
Typical values for f and k for pipes of different materials are listed in Appendix C.