ResearchAc*vi*esinthePar*culateSystemsLaboratory(PSL)Prof.CarlWassgrenSchoolofMechanicalEngineering,PurdueUniversitywassgren@purdue.edu

Ac@vi@esinthePSLfocusondevelopingexperiments,analyses,andcomputersimula@onstomodelthedynamicsofpar*culatesystems,withapplica@onsinmixing,segrega@on,coa@ng,aDri@on,compac@on,granula@on,andcharacteriza@on.Thesemodelshavebeenappliedtosystemsthatprocesspharmaceu@cals,foodandconsumerproducts,biomass,andagrochemicals.

Examplesofcurrentandrecentac@vi@esincludethedevelopmentofpredic@vemodelsfor:•  par@cleandtabletcoa@ng:batchandcon@nuousprocesses,scaling,

inter-andintra-par@cle/tabletcoa@ngvariability,tabletaDri@on•  rigid,needle-shapedpar@cleandflexiblefiberdynamics•  powderrollcompac@onandtable@ng:3DFEMdesignmodels,reduced

ordermodels,materialpropertymeasurements,mixturemodels,pickingands@cking

•  contactspreadingofliquidsinmixedpar@culatesystems•  imagingofgranulecomponentdistribu@onsandtheirinfluenceon

granulestrength•  mixingandsegrega@on:con@nuousblending,mul@-scalesegrega@on

models,segrega@onindischarginghoppers,segrega@oninvibratedbeds,influenceofcohesion

hDps://engineering.purdue.edu/~wassgren/researchPublica@onandThesis

Abstracts

063304-8 Guo et al. Phys. Fluids 25, 063304 (2013)

FIG. 4. Apparent friction coefficient as a function of solid volume fraction for various aspect ratios (µ = 0, e = 0.95,E = 8.7 × 109 Pa, γ = 100 s−1). The kinetic theory curve is for frictionless spheres.

(AR = 0.3, 0.5, 1, and 2), the AFC remains essentially constant at a level higher than the kinetictheory prediction11 when ν is greater than 0.2. However, a sharp decrease in the AFC is observedfor the very flat disks (AR = 0.1) and elongated rods (AR = 4 and 6) at ν > 0.2. This sharp decreasein AFC is attributed to the strong particle alignment that is discussed in Sec. III B.

B. Particle alignment

During dense flows of flat disks and elongated rods, particles exhibit a strong orientationalpreference. As shown in Figure 5, the flat disks have their major axes aligned in the velocitygradient direction (perpendicular to the flow direction) and the rods have their major axes in the flowdirection. With this specific particle orientation, the particle projected area on the plane perpendicularto the flow direction is minimized, and also the particle projected length in the gradient direction(y-direction) is minimized. As a result, the interference between the particles from the same andneighboring layers is reduced.

The orientation of a cylindrical particle can be described using two angles: inclination angle α

and azimuthal angle β, in which α represents the angle between the major axis of the particle and thehorizontal plane and β is the angle between the projection of the major axis and the flow direction(x-direction), as shown in Figure 6(a). Considering the geometric symmetry of the cylinder, both α

and β should run between ±90◦. Figures 6(b) and 6(c) show the probability density distributionsof the inclination angle α and azimuthal angle β, respectively, for the particles of various aspectratios at ν = 0.5. For the particles with the aspect ratio of AR = 1, the probability of α reaches

FIG. 5. Particle alignment during shear flows with (a) disks and (b) elongated rods at a solid volume fraction of 0.5 (µ = 0,e = 0.95, E = 8.7 × 109 Pa, γ = 100 s−1).

This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to IP:128.210.126.199 On: Fri, 19 Dec 2014 23:03:53

Nitin Khola Purdue University

9

Comparison With the Previous Approach

Thursday, January 30, 2014

0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65-2

-1.5

-1

-0.5

0

0.5

1

d/D

ln (u

/(ZD

))

Mean Percolation Velocity (Logarithmic) Dependence on Size Ratio

WALLS WITH FINSROUGH WALLS

Percolation Movie

Y = -5.691X+1.749 R-square: 0.9865

Current ResearchActivitiesintheParticulateSystemsLaboratory (Feb2018)Prof.CarlWassgren (wassgren@purdue.edu)SchoolofMechanicalEngineering,PurdueUniversity

Twinscrewgranulation isarelativelynewcontinuouswetgranulationprocess. Experimentalstudiesareperformedusingrealandidealpharmaceuticalformulationstoelucidatebreakageandnucleationmechanisms.Thegoalistodevelopmodelstopredictgranulesizedistributionsandporosity.

Breakageofneedle-shapedparticles isofsignificantconcerntothepharmaceuticalindustrysincemanyactiveingredientsareneedle-shaped.ComputationalDEMmodelsarebeingdevelopedandusedtoinvestigatethebreakageoftheseparticlesduringprocessing,andtheeffectthatthesesizechangeshaveonthesystemdynamics.

Predictionofblendingandsegregationinindustrialsystemsusingamulti-scalemodelingapproach(FEMandtheadvection-diffusion-segregationequation)isbeingdevelopedandvalidated.Thisapproachisnew,andtheonlypracticalmethod,forsystemsofindustrialinterest.

Shankali Pradhan,Ph.D.student (pradhas@purdue.edu)Jiayu (Billy)Li,UGstudent(li1722@purdue.edu)

Rohit Kumar,Ph.D.student(kumar167@purdue.edu)

YuLiu,Ph.D.student(liu1465@purdue.edu)

Biomassmaterialhandlingmodelsarerequiredtodesigneffectivemethodsforhandlingbiomass,e.g.,switchgrass,woodchips,andcornstover,inbiorefinery storageandfeedingoperations.Inthiswork,FEMandDEMmodelsofbiomassmaterialsarebeingdevelopedandvalidated.

Kunal Pardikar,Ph.D.student(kpardika@purdue.edu)YuLiu,Ph.D.student(liu@purdue.edu)NicoleNeto Godry Farias,UGstudent(nfarias@purdue.edu)

https://engineering.purdue.edu/~wassgren/research

Publication andThesis Abstracts

velocity stress

segregation

Highshearwetgranulation isabatchsizeenlargementprocessforagglomeratingsmallparticlesintolargergranules.Althoughthetechniquehasbeenwidelyusedinpracticefordecades,methodsforpredictinggranulepropertiesandscalingoftheprocessremainlargelyempirical.Currentworkinthelabexaminesscalingmethodologiesandtheuseofx-raycomputedmicrotomography forcharacterizingthegranules.Dr.Dhanajay Pai,LaboratoryManager(dpai@purdue.edu)Jihye (Skylar)Kim,UGstudent(kim1719@purdue.edu)

PredictingGrainDamageinharvestingequipmentisimportantforminimizingcroplosses.CurrentresearchutilizesDEMcomputersimulationsandexperimentstopredictgraindamageduetosurfacewear,impact,andcrushinginvarioussystemfoundincombines.Zhengpu Chen,M.S.student(chen2057@purdue.edu)

blending