title: Particle motion in gas-fluidized granular systems by pulsed-field gradient nuclear magnetic resonance.
abstract: Nuclear magnetic resonance k-space and q-space imaging methods were applied for the first time to monitor the time-averaged density variations and the random motion of granular particles in the presence of gas flow of variable velocity in a model gas-fluidized bed reactor. The transitions toward fluidization, bubbling phase, and slugging phase are visible as sudden changes in the density and the root mean-squared displacement. The onset of these transitions is shown to depend on the particle sizes for a given cell geometry. The effective diffusion coefficients are measured and the distributions of particle displacements, or propagators, are presented.
authors.affiliation: Lehrstuhl für Makromolekulare Chemie, ITMC, RWTH Aachen, Worringerweg 1, D-52074 Aachen, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Savelsberg
authors.forename: Dan E
authors.initials: DE
authors.lastname: Demco
authors.forename: Bernhard
authors.initials: B
authors.lastname: Blümich
authors.forename: Siegfried
authors.initials: S
authors.lastname: Stapf