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Churchill 1973 formula

Values for calculation

$ N_{Re} $
$ ε $ $ \mathrm{m} $
$ D $ $ \mathrm{m} $
$ L $ $ \mathrm{m} $

Calculation

Friction factor

$$f=\left\{2\cdot\log_{10}{\left[\cfrac{ε}{3.7\cdot D}+\left(\cfrac{7}{N_{Re}}\right)^{0.9}\right]}\right\}^{-2}$$

Loss coefficient

$$ζ=f\cdot\cfrac{L}{D}$$