where the second term on the left is the friction head; f is a dimensionless constant called the friction factor, 1L is the pipe length, D is the pipe diameter, and v is the...where the second term on the left is the friction head; f is a dimensionless constant called the friction factor, 1L is the pipe length, D is the pipe diameter, and v is the average fluid velocity (the fluid will flow faster at the center of the pipe than near the edges). For turbulent flow, the analysis to find the friction factor is more complicated and depends on the Reynolds number and the ratio of the pipe surface roughness to pipe diameter.
