Tracking advective flow through floc interior

We experimentally justified the validity of the basic assumption made in most floc models: there exists a strong advection flow through the floc. A swarm of bubbles were generated and released from the bottom of a water pool and rose at the same falling plane of the floc. Information regarding the fluid field, the capture ratio, and the extent of the advection flow were obtained by tracking the interactions of the floc and the bubbles. The advection flow through the floc is found unexceptionable in all tests. The polyelectrolyte flocculation would markedly reduce the extent of advection flow. The floc permeability was estimated based on comparison between experimental findings and the numerical simulations. Copyright ? 2002 The Society of Chemical Engineers.