Scale-up and flow behavior of cohesive granular material in a four-bladed mixer: effect of system and particle size

Veerakiet Boonkanokwong*, Johannes G. Khinast, Benjamin J. Glasser

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Flow of cohesive granular materials with different moisture contents was examined in a four-bladed mixer via the discrete element method (DEM). Firstly, the mixer diameter (D) was increased while keeping the particle diameter (d) constant. It was observed that when the mixer diameter to the particle diameter ratio (D/d) was larger than a certain critical size (D/d ≥ 75), granular flow behaviors and mixing kinetics followed simple scaling relations. For D/d ≥ 75, flow patterns and mixing kinetics were found to be independent of system size, and velocities of particles scaled linearly with the tip speed of the impeller blades and particle diffusivities scaled with the tip speed of the blades and mixer diameter. These results suggest that past a certain system size the flow and mixing of cohesive particles in large-scale units can be predicted from smaller systems. Secondly, system size was kept constant and particle diameter was changed and it was observed that by keeping the Bond number constant (by changing the level of cohesion) the flow behavior and mixing patterns did not change, showing that larger particles can be used to simulate flow of smaller cohesive particles in a bladed mixer by matching the Bond numbers.

Original languageEnglish
Pages (from-to)4481-4495
Number of pages15
JournalAdvanced Powder Technology
Issue number12
Publication statusPublished - Dec 2021


  • Cohesive granular material
  • Discrete element method
  • Pharmaceutical mixing/blending process
  • Scale-up of bladed mixer
  • Solid particulate flow

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Mechanics of Materials


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