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
|hf||Head loss (m)|
|fD||Darcy friction factor (see diagram) (dimensionless)|
|L||Length of the pipe (m)|
|D||Hydraulic diameter (m)|
|V||Average velocity of the fluid flow (m/s)|