Application of Positron Emission Particle Tracking (PEPT) to validate a Discrete Element Method (DEM) model of granular flow and mixing in the Turbula mixer

Positron Emission Particle Tracking (PEPT) experimental measurement technique was employed to compare and validate the Discrete Element Method (DEM) simulation prediction for the motion of particles within the Turbula laboratory scale mixer. The laboratory-scale Turbula mixer comprises a simple cyli...

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Bibliographic Details
Published in:International journal of pharmaceutics 2013-03, Vol.446 (1-2), p.46-58
Main Authors: Marigo, M., Davies, M., Leadbeater, T., Cairns, D.L., Ingram, A., Stitt, E.H.
Format: Article
Language:English
Subjects:
Computer Simulation
DEM
Drug Compounding - instrumentation
Drug Compounding - methods
Electrons
glass
mixing
Particle mixing
PEPT
Powders - chemistry
prediction
Rotation
statistics
Turbula mixer
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Summary:Positron Emission Particle Tracking (PEPT) experimental measurement technique was employed to compare and validate the Discrete Element Method (DEM) simulation prediction for the motion of particles within the Turbula laboratory scale mixer. The laboratory-scale Turbula mixer comprises a simple cylindrical vessel that moves with a complex, yet periodic 3D motion comprising of rotation, translation and inversion. Arising from this complexity, relatively few studies to obtain fundamental understanding of particle motion and mixing mechanisms have been reported. Particle motion within a cylindrical vessel of a Turbula mixer has been measured for 2mm glass spheres using Positron Emission Particle Tracking (PEPT) in a 2l blending mixing vessel at 50% fill level. These data are compared to results from Discrete Element Method (DEM) simulations previously published by the authors. PEPT mixing experiments, using a single particle tracer, gave qualitatively similar trends to the DEM predictions for axial and radial dispersion as well as for the axial displacement statistics at different operational speeds. Both experimental and simulation results indicate a minimum mixing efficiency at ca. 46rpm. The occupancy plots also show a non-linear relationship with the operating speed. These results add further evidence to a transition between two flow and mixing regimes. Despite the similarity in overall flow and mixing behaviour measured and predicted, including the mixing speed at which the flow behaviour transition occurs, a systematic offset between measured and predicted result is observed.
ISSN:0378-5173
1873-3476
DOI:10.1016/j.ijpharm.2013.01.030