Darcy Weisbach equation (head loss)


In fluid dynamics, the Darcy–Weisbach equation is a phenomenological equation, which relates the head loss — or pressure loss — due to friction along a given length of pipe to the average velocity of the fluid flow.
Darcy friction factor can be found from a Moody diagram

Related formulas


hfHead loss (m)
fDDarcy friction factor (see diagram) (dimensionless)
LLength of the pipe (m)
DHydraulic diameter (m)
VAverage velocity of the fluid flow (m/s)
gStandard gravity