| A while back I read a very nice account of the physics as to why the heavier particles settle in the centre. I'm pretty sure it involves an upward force. Stir a cup of tea with tealeaves in it, and a cone of tealeaves forms in the middle.
Centripetal force acts at right angles to the radius of rotation, so the finer particles are thrown out in a spiral and then impact in the boundary layer which is the static layer of water that it 'stuck' to the internal surface of the vortex. If this surface is rough, turbulence will occur that will destroy this smooth undisturbed layer, and the particles will not be able to sink thru it to the bottom, but will, I think be ejected back into the main flow. Peter M basically created multiple surfaces upon which static boundary films formed. You could create the same effect with a non rotating settlement with many sheets of corrugated plastic sheets a small distance apart, so the water was forced to take an undulating path thru it, forcing particles out along its length.
Failing all this, you could simple bin the vortex and place a microscreen over static K. That has a tiny footprint, but enormous solids removal. Plus the screen being fine nylon curtain material is dirt cheap to make.
CAUTION such screens will seize up solid in an hour or two if exposed to daylight. If kept in the dark, they will work brilliantly for months without that happening. |