Atkinson friction factor

This article includes a list of references, related reading, or external links, but its sources remain unclear because it lacks inline citations. Please help improve this article by introducing more precise citations. (October 2021) (Learn how and when to remove this message)

Atkinson friction factor is a measure of the resistance to airflow of a duct. It is widely used in the mine ventilation industry but is rarely referred to outside of it.

Atkinson friction factor is represented by the symbol ${\displaystyle k}$ and has the same units as air density (kilograms per cubic metre in SI units, lbfmin^2/ft^4 in Imperial units). It is related to the more widespread Fanning friction factor by

${\displaystyle k={\frac {1}{2}}\rho f,}$

in which ${\displaystyle \rho }$ is the density of air in the shaft or roadway under consideration and ${\displaystyle f}$ is Fanning friction factor (dimensionless). It is related to the Darcy friction factor by

${\displaystyle k={\frac {1}{2}}\rho {\frac {\lambda }{4}},}$

in which ${\displaystyle \lambda }$ is the Darcy friction factor (dimensionless).

It was introduced by John J Atkinson in an early mathematical treatment of mine ventilation (1862) and has been known under his name ever since.