Laminar Flow Profile
One design constraint is to ensure that the flow is laminar. Turbulent flow cannot be modeled analytically and thus we would not be able to reliably predict plate settler performance.
The entrance region was checked to ensure that the parabolic velocity profile was fully established. This was done by calculating the distance that it will take laminar flow to become fully developed, and make sure that this entrance region is shorter than the length of the tube settler. (Instead of saying what you're doing, show it. Give statistical meaning or values that reflect what you are seeking to do.)
The entrance regions are always less than the length of the plate settlers (Figure 7). Thus, based on this analysis, the best designs would include a plate settler with a larger spacing.