Lattice Boltzmann simulations of low-Reynolds-number flow past fluidized spheres: effect of Stokes number on drag force

Gregory J. Rubinstein, J. J. Derksen, Sankaran Sundaresan*

*Corresponding author for this work

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

In a fluidized bed, the drag force acts to oppose the downward force of gravity on a particle, and thus provides the main mechanism for fluidization. Drag models that are employed in large-scale simulations of fluidized beds are typically based on either fixed particle beds or the sedimentation of particles in liquids. In low-Reynolds-number (Re) systems, these two types of fluidized beds represent the limits of high Stokes number (Si) and low Si, respectively. In this work, the fluid particle drag behaviour of these two regimes is bridged by investigating the effect of Si on the drag force in low-Re systems. This study is conducted using fully resolved lattice Boltzmann simulations of a system composed of fluid and monodisperse spherical particles. In these simulations, the particles are free to translate and rotate based on the effects of the surrounding fluid. Through this work, three distinct regimes in the characteristics of the fluid particle drag force are observed: low, intermediate and high Si. It is found that, in the low-Re regime, a decrease in Si results in a reduction in the fluid particle drag. Based on the simulation results, a new drag relation is proposed, which is, unlike previous models, dependent on St.

Original languageEnglish
Pages (from-to)576-601
Number of pages26
JournalJournal of Fluid Mechanics
Volume788
Early online date8 Jan 2016
DOIs
Publication statusPublished - Feb 2016

Keywords

  • fluidized beds
  • particle/fluid flow
  • suspensions
  • numerical simulations
  • bidisperse arrays
  • equation
  • sedimentation
  • monodisperse
  • bed
  • boundary
  • dynamics
  • automata

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