The Colebrook-White Formula is used for Velocity calculations within the software

where:

V = Velocity, (m/s)

g = Gravitational acceleration

S = Hydraulic gradient (m/m)

v = Kinematic viscosity of fluid (m²/s)

ks = Effective roughness

D = 4 * Hydraulic Radius (m)


Typical ks values for storm drainage are 0.6 mm and 1.5 mm for foul sewage pipes.

Note

InfoDrainage uses a fixed viscosity value of 1 centistoke = 1E-06 m²/s