1993 Volume 19 Issue 6 Pages 1053-1059
The critical tractive condition in dynamic filtration, in which a particulate bed under permeation is swept away by the intensive liquid shear of crossflow, was studied using a rotating ungrooved and grooved disk. Equations were proposed for analysing groove effects on liquid shear, in consideration of three-dimensional flow near the bed. The critical tractive velocity of the rotating disk was determined on the basis of the force balance for a particle in the uppermost layer of the bed. Predicted results using an empirical exposure factor were in satisfactory agreement with experimental data for packed beds of glass beads with particle diamter of 0.151.05mm. It was also shown that grooving decreases the critical rotation of the disk quite appreciably and is beneficial for sweeping the granular bed.
