= Loss of head due to friction in meters.
= Pressure drop in Pascals.
f = Colebrook friction factor (Moody’s chart)
L = Length of the pipe in meters.
v = Velocity of fluid in m/s.
= Fluid density in kg/m3.
g = Acceleration due to gravity (9.8 m/s²).
d = Inner diameter of pipe in meters.
Coolebrook equation :
Re = Reynolds number, dimensionless
ϵ = absolute roughness of pipe wall in m.