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The Fanning friction factor (named after American engineer John T. 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 density: [ 1 ] [ 2 ]
If the value of the friction factor is 0.016, then the Fanning friction factor is plotted in the Moody diagram. Note that the nonzero digits in 0.016 are the numerator in the formula for the laminar Fanning friction factor: f = 16 / Re . The procedure above is similar for any available Reynolds number that is an integer power of ten.
Friction factor may refer to: Atkinson friction factor, a measure of the resistance to airflow of a duct; Darcy friction factor, in fluid dynamics; Fanning friction factor, a dimensionless number used as a local parameter in continuum mechanics
In this article, the following conventions and definitions are to be understood: The Reynolds number Re is taken to be Re = V D / ν, where V is the mean velocity of fluid flow, D is the pipe diameter, and where ν is the kinematic viscosity μ / ρ, with μ the fluid's Dynamic viscosity, and ρ the fluid's density.
where is the density of the fluid, is the average velocity in the pipe, is the friction factor from the Moody chart, is the length of the pipe and is the pipe diameter. The chart plots Darcy–Weisbach friction factor f D {\displaystyle f_{D}} against Reynolds number Re for a variety of relative roughnesses, the ratio of the mean height of ...
is Darcy friction factor; in addition to the terms defined above. Atkinson also defined a friction factor (Atkinson friction factor) used for airways of fixed section such as shafts. It accounts for Fanning friction factor, density and the constant / and relates to Atkinson resistance by
Assuming the Fanning friction factor is a constant along the duct wall, the differential equation can be solved easily. [2] [3] One must keep in mind, however, that the value of the Fanning friction factor can be difficult to determine for supersonic and especially hypersonic flow velocities.
= Fanning friction factor, = Sum of all kinetic energy factors in system Once calculated, the total head loss can be used to solve the Bernoulli Equation and find unknown values of the system. [1] [5]