MOTION AND DEPOSITION OF NON-BROWNIAN PARTICLES IN UPFLOW COLLECTORS

The motion and deposition of suspended particles in upflow unit cells of sinusoidal shape are studied using a three-dimensional trajectory a nalysis. Particle stagnation and exclusion regions can develop at the entrance mouth of upflow cells, the extent and distribution of which d epend on several parameters including particle size, flow rate, cell g eometry, and cell inclination. It is found that the particle exclusion phenomenon can become very significant over a wide range of the prece ding parameters and can have significant implications in network-based simulations of upflow or horizontal flow depth filtration. A new defi nition of the impacted fraction is introduced that is based on the par ticle entrance velocity and the actual entrance region. Calculations o f the deposition rate in sinusoidal collectors indicate that switching from a down flow to an upflow mode results in increased or decreased capture efficiency depending, chiefly, on the inclination of the unit collector.