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Haaland equation

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The Haaland equation is an approximate explicit equation which combines experimental results of studies of laminar and turbulent flow in pipes. It was developed by S. E. Haaland in 1983.

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The Haaland equation is defined as:

$\frac{1}{\sqrt {f}} = -1.8 \log \left[ \left( \frac{\varepsilon/D}{3.7} \right)^{1.11} + \frac{6.9}{\mathrm{Re}} \right]$

where:

$f$ is the Darcy friction factor
$\varepsilon/D$ is the relative roughness
$Re$ is the Reynolds number

References

Haaland, SE (1983). "Simple and Explicit Formulas for the Friction Factor in Turbulent Flow". Trans. ASIVIE, J. of Fluids Engineering 103: 89-90.

Category: Fluid dynamics