Swamee-Jain Equation

Written by Jerry Ratzlaff on . Posted in Fluid Dynamics

The Swamee-Jain Equation can be used to solve the Darcy-Weisbach friction factor for a full-flowing pipe and is accurate to 1.0% of the Colebrook-White Equation for  \(\large{  10^{-6} < \frac{\epsilon}{d} < 10^{-2} }\)  and  \(\large{ 5,000 < Re < 10^8  }\).

 

swamee-jain equation formulas

\(\large{  f = \frac{0.25}{[log \; (\frac{\epsilon}{3.7\;d} + \frac{5.74}{Re^{0.9}})]^2}  }\) 
\(\large{  f = \frac{0.25}{log_{10} \; (\frac{  \frac{\epsilon}{ d }  }{3.7} + \frac{5.74}{Re^{0.9}})^2}  }\) 

Where:

 Units English SI
\(\large{ f }\) = friction factor \(\large{ dimensionless }\)
\(\large{ \epsilon }\)  (Greek symbol epsilon) = absolute roughness \(\large{ in }\) \(\large{ mm }\)
\(\large{ d }\) = inside diameter of pipe \(\large{ in }\) \(\large{ mm }\)
\(\large{ Re }\) = Reynolds number \(\large{ dimensionless }\)

 

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Tags: Friction Equations Flow Equations