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Stochastic analysis of a three‐phase fluidized bed: Fractal approach
Author(s) -
Fan L. T.,
Neogi D.,
Yashima M.,
Nassar R.
Publication year - 1990
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690361008
Subject(s) - hurst exponent , fractal dimension , fluidized bed , fractional brownian motion , rescaled range , fractal , brownian motion , fluidization , statistical physics , series (stratigraphy) , mathematics , stochastic process , range (aeronautics) , mechanics , detrended fluctuation analysis , thermodynamics , materials science , physics , statistics , mathematical analysis , scaling , geology , geometry , paleontology , composite material
Three‐phase fluidized beds have played important roles in various areas of chemical and biochemical processing. The characteristics of such beds are highly stochastic due to the influence of a variety of phenomena, including the jetting and bubbling of the fluidizing medium and the motion of the fluidized particles. A novel approach, based on the concept of fractals, has been adopted to analyze these complicated and stochastic characteristics. Specifically, pressure fluctuations in a gas‐liquid‐solid fluidized bed under different batch operating conditions have been analyzed in terms of Hurst's rescaled range (R/S) analysis, thus yielding the estimates for the so‐called Hurst exponent, H . The time series of the pressure fluctuations has a local fractal dimension of d FL = 2 − H . An H value of ½ signifies that the time series follows Brownian motion; otherwise, it follows fractional Brownian motion (FBM), which has been found to be the case for the three‐phase fluidized bed investigated.