Darcy Friction Factor - Free Surface Flow

Written by Jerry Ratzlaff on . Posted in Fluid Dynamics

Darcy friction factor formulas are equations that allow you to calculate the friction losses in pipe flow and open channel flow. Free surface flow describes flow that experiences zero shear forces.  An example of this is open channel flow, such as a canal used for shipping or irrigation.  The Darcy friction factor is used in the Darcy-Weisbach equation to determine pressure drop.


Formulas that use Darcy Friction Factor - Free Surface Flow

\(\large{ \frac{1}{ \sqrt{f_d} } =  -2\; log_{10}  \; \left( \frac{ \epsilon }{ 12 \; r_h } + \frac{ 2.51 }{ Re \; \sqrt{f_d} } \right) }\)   


\(\large{ f_d }\) = Darcy friction factor

\(\large{ r_h }\) = hydraulic radius

\(\large{ \epsilon }\)  (Greek symbol epsilon) = pipe's effective roughness height

\(\large{ Re }\) = Reynolds number


Tags: Equations for Friction