Friction Factor

The friction factor has been established to base on the Reynolds number for the flow and the degree of coarseness of the pipe's inner surface.

The quantity employed to measure the roughness of the pipe is termed as the relative roughness, that equivalents the average height of surface irregularities (ε) divided by the pipe diameter (D).

Relative Roughness = ε/D

The value of the friction factor is generally acquired from the Moody Chart. The Moody Chart can be employed to determine the friction factor depend on the Reynolds number and the relative roughness.