physics - Darcy Friction factor

The Darcy friction factor is a dimensionless number used in internal flow calculations. It expresses the linear relationship between mean flow velocity and pressure gradient .

It is defined as:

$f = \frac{(\frac{-d p*}{d x}) D_h}{0.5 \rho V^2}$

where:

$\frac{-d p*}{d x}$ is the pressure drop per unit length

$D h$ is the hydraulic diameter

ρ is the fluid density

V is the bulk velocity

Categories: Dimensionless numbers