This paper present a study of the dynamic behavior of individual particles during the segregation process of particle mixtures in a gas fluidized bed. The so-called microdynamic analysis is made based on the results generated from discrete particle simulation, with the focus on the trajectory of and forces acting on individual particles. Three typical particles are selected representing three kinds of particle motions: a flotsam particle which is initially at the bottom part of the bed and finally fluidized at the top part of the bed; a jetsam particle which is initially at the top part of the bed and finally stays in the bottom de-fluidized layer of the bed; and a jetsam particle which is intermittently joining the top fluidized and bottom de-fluidized layer. The behaviour of the three particles are analyzed in details and explained in terms of their interaction forces and contact conditions with other particles, particle-fluid interaction force, and local flow structure. The results are useful to understand the local flow structures and the mechanisms governing particle mixing/segregation in gas fluidization.
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