Jamming transition in emulsions and granular materials.pdf

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1、PHYSICALREVIEWE72,011301
2005JammingtransitioninemulsionsandgranularmaterialsH.P.ZhangPhysicsDepartment,CityCollegeofNewYork,NewYork10031,USAH.A.MaksePhysicsDepartmentandLevichInstitute,CityCollegeofNewYork,NewYork10031,USA
Received16January2005;pub

2、lished7July2005Weinvestigatethejammingtransitioninpackingsofemulsionsandgranularmaterialsviamoleculardy-namicssimulations.Theemulsionmodeliscomposedoffrictionlessdropletsinteractingvianonlinearnormalforcesobtainedusingexperimentaldataacquiredbyconfo

3、calmicroscopyofcompressedemulsionssystems.GranularmaterialsaremodeledbyHertz-MindlindeformablesphericalgrainswithCoulombfriction.Inbothcases,weÞndpower-lawscalingforthevanishingofpressureandexcessnumberofcontactsasthesystemapproachesthejammingtransit

4、ionfromhighvolumefractions.WeÞndthattheconstructionhistoryparam-etrizedbythecompressionrateduringthepreparationprotocolhasastrongeffectonthemicromechanicalpropertiesofgranularmaterialsbutnotonemulsions.Thisleadsthegranularsystemtojamatdifferentvolume

5、fractionsdependingonthehistories.IsostaticityisfoundinthepackingsclosetothejammingtransitioninemulsionsandingranularmaterialsatslowcompressionratesandinÞnitefriction.Heterogeneityofinterpar-ticleforcesincreasesasthepackingsapproachthejammingtransitio

6、nwhichisdemonstratedbytheexponen-tialtailinforcedistributionsandthesmallvaluesoftheparticipationnumbermeasuringspatiallocalizationoftheforces.However,nosignaturesofthejammingtransitionareobservedinstructuralproperties,liketheradialdistributionfunctio

7、nsandthedistributionsofcontacts.DOI:10.1103/PhysRevE.72.011301PACSnumber
s:81.05.RmI.INTRODUCTIONingsarecharacterizedbyelasticHertz-Mindlinforces17Ð19withCoulombfriction.Concentratedemulsionsys-Avarietyofsystemssuchasgranularmaterials,com-temsarem

8、odeledasacollectionoffrictionlessdeformablepressedemulsions,ormolecularglasses,exhibitanonequi-dropletsinteractingviaanonlinearnormalforcelawwhichlibriumtransitionfromaßuidliketoasolidlikestate.Whenisobtainedfromtheanalysisofexperimentaldataacquiredt