title: Power-law distribution of pressure fluctuations in multiphase flow.
abstract: 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.
authors.affiliation: Department of Chemical Technology, Delft University of Technology, Julianalaan 136, The Netherlands. S.Gheorghiu@tnw.tudelft.nl
authors.forename: S
authors.initials: S
authors.lastname: Gheorghiu
authors.forename: J R
authors.initials: JR
authors.lastname: van Ommen
authors.forename: M-O
authors.initials: MO
authors.lastname: Coppens