Granular temperature in a gas fluidised bed

Mark J. Biggs, Liansong Xie, Don Glass, Vladimir Zivkovic, M. A. Curt Koenders

Research output: Contribution to conferencePaperpeer-review


Contradictory evidence over the role of bubbles in inducing particle velocity fluctuations has been presented in the literature - are bubbles required to induce particle velocity fluctuations in gas FBs or not? Applying the non-intrusive method of diffusing-wave spectroscopy (DWS) to a gas fluidised bed of particles whose minimum bubbling velocity is ~5 times that of the minimum fluidisation velocity, it is shown that bubbles are not necessary. Fluctuations are first observed at or just above fluidisation and increase in magnitude with superficial velocity. Following Batchelor (1988), assuming the square of the fluctuations are proportional to the square of the superficial velocity, (δv)2 =f(θ) Us2 the function f(θ) was found to rise from zero at a voidage of θ≈ 32% to a maximum around θ≈ 40% from where it tails off to zero at θ≈52%. The distribution of velocity fluctuations in the bed is also presented. They are symmetrical about the centreline where they are maximal and increase with height above the distributor.

Original languageEnglish
Publication statusPublished - 2006
Event2006 AIChE Spring National Meeting - 5th World Congress on Particle Technology - Orlando, FL, United States
Duration: 23 Apr 200627 Apr 2006


Conference2006 AIChE Spring National Meeting - 5th World Congress on Particle Technology
Country/TerritoryUnited States
CityOrlando, FL


  • Granular temperature
  • Kinetic theory
  • Rapid granular flows

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Chemistry(all)


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