Sub-grid drag models for horizontal cylinder arrays immersed in gas-particle multiphase flows

Avik Sarkar, Xin Sun, Sankaran Sundaresan

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

Immersed cylindrical tube arrays often are used as heat exchangers in gas-particle fluidized beds. In multiphase computational fluid dynamics (CFD) simulations of large fluidized beds, explicit resolution of small cylinders is computationally infeasible. Instead, the cylinder array may be viewed as an effective porous medium in coarse-grid simulations. The cylinders' influence on the suspension as a whole, manifested as an effective drag force, and on the relative motion between gas and particles, manifested as a correction to the gas-particle drag, must be modeled via suitable sub-grid constitutive relationships. In this work, highly-resolved unit-cell simulations of flow around an array of horizontal cylinders, arranged in a staggered configuration, are filtered to construct sub-grid, or 'filtered', drag models, which can be implemented in coarse-grid simulations. The force on the suspension exerted by the cylinders is composed of, as expected, a buoyancy contribution, and a kinetic component analogous to fluid drag on a single cylinder. Furthermore, the introduction of tubes also is found to enhance segregation at the scale of the cylinder size, which, in turn, leads to a reduction in the filtered gas-particle drag.

Original languageEnglish (US)
Pages (from-to)399-412
Number of pages14
JournalChemical Engineering Science
Volume104
DOIs
StatePublished - Dec 18 2013

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)
  • Industrial and Manufacturing Engineering

Keywords

  • Computational fluid dynamics (CFD)
  • Cylinders
  • Filtered models
  • Fluidization
  • Multiphase flow
  • Multiscale

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