A DEM study of particle motion near the walls of gas fluidized beds

This paper presents an investigation, by discrete element method simulation, of particle motion near the walls of fluidized beds. The simulations were performed in two beds, one of 50 mm × 50 mm cross-section, and the other of 90 mm × 90 mm cross-section. The particles used were 0.5 and 1 mm in diameter and 2650 kg/m3 in density. It was found that the thickness of the down-flowing surface layer is around 15 times the particle diameter. The average downward velocity of particles in the surface layer was found to vary from about 0.01 to 0.2 m/s. Implication of the results in relation to understanding of bed-to-wall heat-transfer in fluidized beds is highlighted.