Darcy friction factor - Goudar–Sonnad equation
In fluid dynamics, the Darcy friction factor formulae are equations that allow the calculation of the Darcy friction factor, a dimensionless quantity used in the Darcy–Weisbach equation, for the description of friction losses in pipe flow as well as open-channel flow.
The Darcy friction factor is also known as the Darcy–Weisbach friction factor, resistance coefficient or simply friction factor; by definition it is four times larger than the Fanning friction factor.
Goudar equation is the most accurate approximation to solve directly for the Darcy–Weisbach friction factor f for a full-flowing circular pipe. It is an approximation of the implicit Colebrook–White equation.
The variables (a), (d), (q) and (D_CFA) can be calculated using these formulas.
Variable (a) formula
Variable (d) formula
Variable (q) formula
Variable (D_CFA) formula
|f||Darcy friction factor (dimensionless)|
|a||Variable in Goudar–Sonnad equation (dimensionless)|
|d||Variable in Goudar–Sonnad equation (dimensionless)|
|q||Variable in Goudar–Sonnad equation (dimensionless)|
|DCFA||Variable in Goudar–Sonnad equation (dimensionless)|