Analysis of floc structure based on the extended Brinkman model.

The extended Brinkman model for flocculated dispersion is presented. This model can describe fluid flow relative to a swarm of flocs over a wide concentration range. The theoretical floc density function is derived by combining the model with the permeability data in a concentrated region where individual flocs contact each other. For flocculated polystyrenes consisting of non-porous, impermeable, and spherical particles of submicron size, the density, the aggregation number, and the projected area diameter of a floc were determined by the sedimentation method, the drying method, and the photographic method, respectively. The permeability data in dilute and concentrated regions were obtained by the sedimentation test and the constant-rate expression method, respectively. Agreement between the theoretical floc density function and experimental floc characteristics was satisfactory. The floc morphology was strongly reflected in the permeability characteristic in a concentrated region. It was found that the overall solidosity when complete floc breakage occurs is approximately equal to that of the loosest packing structure if a sphere bed.