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Autori: S. Gheorghiu, J. R. van Ommen, and M.-O. Coppens
Editorial: Physical Review E (PRE), 67, p.041305, 2003.
Bubbling fluidized beds are granular systems, in which a deep layer of particles is set in motion by a vertical gas stream, with the excess gas rising as bubbles through the bed. We show that pressure fluctuations in such a system have non-Gaussian statistics. The probability density function has a power-law drop-off and is very well represented by a Tsallis distribution. Its shape is explained through the folding of the Gaussian distribution of pressure fluctuations produced by a monodisperse set of bubbles, onto the actual distribution of bubble sizes in the bed, assuming that bubbles coalesce via a Smoluchowski-type aggregation process. Therefore, the Tsallis statistics arise as a result of bubble polydispersity, rather than system nonextensivity.
Cuvinte cheie: multiphase flow, fluidization, fluidized bed, bubble size, statistics, power law, polydispersity