(114b) Agglomeration and De-Agglomeration of Wetted Solids: A Summary of Recent Findings

Liquid-coated, solid particles occur in a wide variety of applications – filtration, agitated drying, and granulation, to name a few.  Much of the past work on these systems has focused on the agglomeration behavior of two-particle collisions that occur in the normal (head-on) direction.  Over the past several years, we have extended this work by considering two cases in details:  (i) the normal collision of 3 wetted particles, and (ii) the oblique collision of 2 wetted particles.  The experiments are rich in surprising results, and have shed light on important physical mechanisms previously believed to be negligible.  Corresponding advances in the theoretical description have ensued, including the important role of glass transition, added resistance upon rebound from existing liquid bridges, capillary forces even for high Capillary-number flows, and a new de-agglomeration mechanism characterized by a dimensionless number relating centrifugal forces to capillary forces. An overview of these findings will be given.