Proper-orthogonal decomposition of spatio-temporal patterns in fluidized beds
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Numerical simulations of the hydrodynamics of a fluidized bed are carried out to investigate the complex interaction between the gas and the solid particles, and to explore the utility of a reduced-order model based on the proper orthogonal decomposition (POD). The behavior of a fluidized bed is modeled using a "two- fluid" theory, which involves conservation of mass, momentum, energy and species equations for the two interpenetrating continua. These equations are solved using a numerical algorithm that employs a conservative discretization scheme with mixed implicit and explicit formulations. We conducted simulations of gas-solid interaction in a narrow (two-dimensional) bed filled with sand particles which was uniformly fluidized at minimum fluidization but with additional air flow through a central nozzle. Aided by the proper orthogonal decomposition, spatial dominant features are identified and separated from the spatio-temporal dynamics of the simulations. The most dynamic region of the gas-solid interaction is confined to the central channel caused by the jet. The flow within this structure is successfully captured by a few POD eigenfunctions. Phase-space plots further indicate the existence of low-dimensional dynamics within the central channel. This conclusion supports the validity of a reduced-order model for fluidized beds, which can then be constructed by projecting the governing equations onto the POD modes, as it is commonly done in the Galerkin method. © 2003 Elsevier Ltd. All rights reserved.
author list (cited authors)
Cizmas, P. G., Palacios, A., O'Brien, T., & Syamlal, M.