Swamee-Jain equation
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The Swamee-Jain equation is used to solve directly for the Darcy-Weisbach friction factor f for a full-flowing circular pipe. It is an approximation of the implicit Colebrook-White equation.
![f = \frac{0.25}{[log (\frac{\epsilon}{3.7D} + \frac{5.74}{Re^{0.9}})]^2}](../../../math/4/7/b/47b1576392bdce0c754aa2c9a9225a2d.png)
Where f is a function of:
- roughness height, ε (m, ft)
- pipe diameter, D (m, ft)
- Reynolds number, Re (unitless).
The equation was found to match the Colebrook-White equation within 1.0% for 10-6 < ε/D < 10-2 and 5000 < Re < 108.
[edit] Reference
- 1976, Swamee, P.K. and Jain, A.K., Explicit equations for pipe-flow problems, Journal of the Hydraulics Division, ASCE, 102, HY5, 657-664
