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PowerPoint PresentationModeling Granular Material Mixing and Segregation Using a Multi-Scale Model Yu Liu, Prof. Marcial Gonzalez, Prof. Carl Wassgren
School of Mechanical Engineering, Purdue University, West Lafayette, IN
Motivation Granular material mixing and segregation • Granular material mixing and segregation plays an important role in many
industries ranging from pharmaceuticals to agrochemicals • Predictive engineering design of industrial powder blenders remains
underdeveloped due to the lack of quantitative modeling tools
Objective Develop a predictive model of granular material mixing and segregation for industrial equipment • Quantitatively predict the magnitude and rate of powder mixing and segregation • Be capable of modeling industrial-scale equipment • Demonstrate understanding to regulators in particle mixing and segregation
Multi-Scale Model
Diffusion correlations (3-D) • is an anisotropic tensor instead of an isotropic value • Off-diagonal components and are an order of magnitude smaller than the
diagonal components and
Utter et al. (2004, Phys Rev Lett, Vol. 69); Hsiau et al. (1999, J. Rheol, Vol. 43)
• = 1 2 + 2( + ) 2
2 = 1.91 according to Utter et al. (2004 , Phys Rev Lett, Vol. 69) 1 can be calibrated from DEM simulations or experiments
Segregation correlations (2-D) • Percolation is one of the most important mechanisms causing segregation • acts in the direction of gravity
• According to Fan et al. (2014, J. Fluid Mech, Vol. 741): , = (1 − ) & , = − (1 − )
can be calibrated from DEM simulations or experiments
FEM Model Model implementations • The commercial FEM package Abaqus V6.14 is used to perform the simulations • The Coupled Eulerian-Lagrangian (CEL) approach in Abaqus is applied to handle
highly deformable material elements • Within the Eulerian domain, the material stress-strain behavior is modeled using
the Mohr-Coulomb elastoplastic (MCEP) model • Material properties can be measured from independent, standard tests
Bulk internal friction angle and cohesion => Shear test Bulk wall friction angle => Shear test Young’s Modulus and Poisson’s ratio => Uniaxial compression test
FEM simulation results – velocity profile • Rotating drum
• Conical and wedge-shaped hopper
• V blender and Tote blender
3-D Tote blender - mixing • Compared with published experiments of binary mixing of glass beads in an industrial-
scale Tote blender from Sudah et al. (2005, AIChE J., Vol. 51) • All the parameters were calibrated from independent experiments • Predictions of the mixing rate (relative standard deviation, RSD) from the multi-scale
model compare well quantitatively to the published experimental data
2-D rotating drum - segregation • Compared with published DEM simulations of binary segregation in a lab-scale rotating
drum from Schlick et al. (2015, J. Fluid Mech, Vol. 765) • All the parameters were derived directly from the published work • Predictions compare well quantitatively to DEM results
2-D conical hopper - segregation • Compared with published experiments of binary segregation of glass beads in different
conical hoppers from Ketterhagen et al. (2007, Chem Eng Sci, Vol. 62) • All the parameters were calibrated directly from the published work • Predictions from the multi-scale model compare well quantitatively to experiments
Macroscopic scale model • Predicts: advective flow field • Depends on: system geometries material bulk properties boundary conditions
• Method used: FEM
Microscopic scale model • Predicts: local diffusion / segregation rates • Depends on: particle properties local material concentration local shear rate and and solid fraction
• Method used: DEM / Experiments
= − + −
Conical Wedge-shaped
FEM simulations
Conical Wedge-shaped
DEM simulations
Side-Side Top-Bottom
Results 2-D rotating drum - mixing • Compared with DEM simulations of binary mixing in a lab-scale rotating drum • All the parameters were derived from published work by Fan et al. (2015, Phys Rev
Lett, Vol. 115) • Predictions of concentration profiles from the multi-scale model compare well
quantitatively to DEM results
Multi-scale model predictionsFEM simulations
DEM simulation Multi-scale model
Concentration of red particles
Concentration of small particles
Concentration of small particles

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