Atkinson friction factor is a measure of the resistance to airflow of a duct. It is widely used in the

mine ventilation Underground mine ventilation provides a flow of air to the underground workings of a mine of sufficient volume to dilute and remove dust and noxious gases (typically NOx, SO2, methane, CO2 and CO) and to regulate temperature. The source of ...

industry but is rarely referred to outside of it. Atkinson friction factor is represented by the symbol

k

and has the same units as air density (kilograms per cubic metre in

SI units The International System of Units, known by the international abbreviation SI in all languages and sometimes pleonastically as the SI system, is the modern form of the metric system and the world's most widely used system of measurement. E ...

, lbfmin^2/ft^4 in

Imperial unit The imperial system of units, imperial system or imperial units (also known as British Imperial or Exchequer Standards of 1826) is the system of units first defined in the British Weights and Measures Act 1824 and continued to be developed th ...

s). It is related to the more widespread

Fanning friction factor The Fanning friction factor, named after John Thomas Fanning, is a dimensionless number used as a local parameter in continuum mechanics calculations. It is defined as the ratio between the local shear stress and the local flow kinetic energy ...

k = \frac\rho f,

in which

\rho

is the

density of air The density of air or atmospheric density, denoted '' ρ'', is the mass per unit volume of Earth's atmosphere. Air density, like air pressure, decreases with increasing altitude. It also changes with variation in atmospheric pressure, temperatur ...

in the shaft or roadway under consideration and

f

is Fanning friction factor (dimensionless). It is related to the

Darcy friction factor Darcy, Darci or Darcey may refer to: Science * Darcy's law, which describes the flow of a fluid through porous material * Darcy (unit), a unit of permeability of fluids in porous material * Darcy friction factor in the field of fluid mechanics ...

k = \frac\rho \frac{4},

in which

\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.

References

* NCB Mining Dept., ''Ventilation in coal mines: a handbook for colliery ventilation officers,'' National Coal Board 1979.

See also

References

Further reading