The Mechanical Engineering Handbook



Darcy-Weisbach Equation

Darcy-Weisbach Equation



$$ h_f = f \cdot \frac{L}{D} \cdot \frac{v^2}{2g} $$ where:

hf   =   Head Loss   (m)

f   =   Darcy Friction Factor   (dimensionless)

L   =   Length of pipe   (m)

D   =   Diameter of the pipe   (m)

v   =   Flow velocity   (m/s)

g   =   Gravitational Acceleration   (m/s²)


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Equation Assumptions



  • The fluid is incompressible and Newtonian.
  • The fluid is in a steady flow.
  • The flow is fully developed.
  • There are no significant local energy losses.