# Darcy friction factor - Brkić solution

## Description

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.

Brkić shows one approximation of the Colebrook equation based on the Lambert W-function. The equation was found to match the Colebrook–White equation within 3.15%.

**See Also:**

Darcy friction factor – Brkić solution – Variable S

Related formulas## Variables

f | Darcy friction factor (dimensionless) |

ϵ | Pipe's effective roughness height (m) |

D | Pipe's inside diameter (m) |

S | Variable in Brkić solution (dimensionless) |

Re | Reynolds number (dimensionless) |