| I understand the small vs. large particle differences, and drag coefficient of the wall. But, I am not positive I understand the force that pushes particles towards the center of a gyre.
Increasing the drag coefficient of the wall surface may not be advantageous. Yes, it will result in more debris being pulled out of suspension. However, the goal is to remove the debris from the system entirely before it decomposes further and releases nitrogenous compounds and DOM to the water. Barring micro-screen filtration, the most efficient way to remove debris from the system is to "spin" it to the center of a swirl separator where it can be entrained and dumped when the waste valve is opened. By roughening the wall texture, you impede migration of settled debris along the tank surface towards the waste port. This is no better than adding matala mat, brushes or other substrate to the separation tank. Yes, you catch debris, but it is not removed from the system until the substrate is taken out and hosed off. Its a nasty job and it is not practicle to remove and clean the substrate, or to wash down the walls of the tank, on a frequent basis, so the stuff just sits there and decomposes. It is practical to open the waste valve on a frequent basis and dump debris which has collected near the bottom of the cone. But to make it work, the separator tank capacity and bottom slope must be properly sized to the flow.
I am on the northwest corner of Kaneohe Bay, three miles past Hygienic Store.
steve |