...
The particle velocity expereince as a result of the velocity gradient can be expressed as follows:
insert vparticle here
where phi is the shape factor, equivalent to 45/24
Therefore, the ratio can be expressed as
insert velocity ratio formula here
When this ratio is greater than one (ie the settling velocity is greater than the velocity experienced by the floc particles in the tube), the flocs will fall back into floc blanket and fail to travel to the effluent. When this ratio is equal to one, the particles will remain stationary in the tube settler. And when the ratio is less than one, the velocity of the particles will exceed the settling velocity and the floc particles will roll up into the effluent, creating a highter turbidity.
...