Flow velocity: Darcy–Weisbach Friction Factor and Equation

The Darcy–Weisbach Friction Factor relates shear velocity to mean flow velocity.

Learning Goals

• See the Darcy–Weisbach equation as analogous to the Chézy equation, but with the advantage of linking mean and shear velocities.

Useful Equations

For quick reference; see course notes and video for derivation:

\[\tau_b = \rho C_f \bar{u}^2 = \rho u_\tau^2\]

Therefore,

\[u_\tau = \rho C_f \bar{u}^2\] \[\bar{u} = \frac{1}{\sqrt{C_f}} u_\tau\]

Course notes

Flow mechanics PDF

The Darcy–Weisbach Equation and Friction Factor, \(C_f\)

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