简介：Bothclinicalandpostmortemstudiesindicatethat,inhumans,thecarotidsinusofthecarotidarterybifur-cationisoneofthefavoredsitesforthegenesisanddevelop-mentofatheroscleroticlesions.Hemodynamicfactorshavebeensuggestedtobeimportantinatherogenesis.Tounderstandthecorrelationbetweenatherogenesisandfluiddynamicsinthecarotidsinus,thebloodflowinarterywassimulatednumerically.Inthosestudies,thepropertyofbloodwastreatedasanincompressible,Newtonianfluid.Infact,however,thebloodisacomplicatednon-Newtonianfluidwithshearthinningandviscoelasticproperties,especiallywhentheshearrateislow.Avarietyofnon-Newtonianmod-elshavebeenappliedinthenumericalstudies.Amongthem,theCassonequationwaswidelyused.However,theCas-sonequationagreeswellonlywhentheshearrateislessthan10s~(-1).Theflowfieldofthecarotidbifurcationusuallycoversawiderangeofshearrate.WethereforebelievethatitmaynotbesufficienttodescribethepropertyofbloodonlyusingtheCassonequationinthewholeflowfieldofthecarotidbifurcation.Inthepresentstudy,threedifferentbloodconstitutivemodels,namely,theNewtonian,theCas-sonandthehybridfluidconstitutivemodelswereusedintheflowsimulationofthehumancarotidbifurcation.Theresultswerecomparedamongthethreemodels.TheresultsshowedthattheNewtonianmodelandthehybridmodelhadverysimilardistributionsoftheaxialvelocity,secondaryflowandwallshearstress,buttheCassonmodelresultedinsignificantdifferencesinthesedistributionsfromtheothertwomod-els.ThisstudysuggeststhatitisnotappropriatetoonlyusetheCassonequationtosimulatethewholeflowfieldofthecarotidbifurcation,andontheotherhand,Newtonianfluidisagoodapproximationtobloodforflowsimulationsinthecarotidarterybifurcation.