Mean Velocity in Fluid

In fluids, the velocity is not constant.  In a fluid in motion, the velocity is zero at the wall and increases symmetrically towards the center.  This is known as the velocity profile.  The velocity is maximum at the center.

The mean velocity is average value of the velocity of the individual layers.

In pipelines with constant cross section.

The velocity of the fluid can be calculated from the discharge if the cross sectional area is known.

Velocity = Discharge / Area