简介：Newtonian,QuemadaandCassonbloodviscositymodelsareimplementedinordertosimulatetherheologicalbehaviorofbloodunderpulsatingflowconditionsinapatientspecificiliacbifurcation.Theinfluenceoftheappliedbloodconstitutiveequationsismonitoredviathewallshearstress(WSS)distribution,magnitudeandoscillations,non-Newtonianimportancefactors,andviscosityvaluesaccordingtotheshearrate.ThedistributionofWSSonthevascularwallfollowsapatternwhichisindependentoftherheologicalmodelchosen.Ontheotherhand,theWSSmagnitudeandoscillationsaredirectlyrelatedtothebloodconstitutiveequationsappliedandtheshearrate.ItisconcludedthattheNewtonianapproximationissatisfactoryonlyinhighshearandflowrates.Moreover,theNewtonianmodelseemstooverestimatethepossibilityfortheformationofatheroscleroticlesionsoraneurysmsatsitesofthevascularwallwheretheWSSareoscillating.

简介：Basedonestablishednumericalmethodsandhydrodynamicperformancetestingfacilities,CFDtechniqueareappliedtoimprovethedesignoftheimplantableaxialflowbloodpumpandtheflowanalysis.(1)Applyingbrushlessmachinemagnetsteel,reducingitsthicknesswhileincreasingthelength,theflowchannel'scross-sectionisincreased,withnospaceconnectionbetweenthelargeandthesmallrotators,andwithaconetransitionsegmentfromthebearingtotheprincipalaxis,theflowismadesmoother.Therotatingspeedisloweredby1000rpm-1200rpmunderthesameflowrateandpressurehead,andthusthehemolysiscanbeavoided.(2)Differentoutletstatorguidingvanesareselectedforthesamebloodpumpforanalysesofhydrodynamicperformancesandflowfields.Anexcellentdesignnotonlycanregulatetherotatingflowfieldintoanaxialone,reducethecirculationlossandimprovethepumpefficiency,butalsocanavoidbackflow,vortexandsecondaryflowatthepumpoutlet,andthusthethrombuscanbeprevented.(3)Thecalflivetestsshowthatsomeresidualclotsexistattheinnerwalloftheoutletconnectionbends,whichareanalyzedandexplainedbyCFDtechniquesandthecorrespondingimprovementsareproposed.AllresultsareverifiedbyhydrodynamicperformancetestsandPIVflowfieldtests,andconsistentconclusionsareobtained.

简介：Anumericalanalysisofnon-Newtonianfluidflowinnon-planararterywithbifurcationwasperformedbyusingafiniteelementmethodtosolvethethree-dimensionalNavier-Stokesequationscoupledwiththenon-Newtonianconstitutivemodels,includingCarreau,CrossandBinghammodels.Theobjectiveofthisstudyistoinvestigatetheeffectsofthenon-Newtonianpropertiesofbloodaswellascurvatureandout-of-planegeometryinthenon-planardaughtervesselsonthevelocitydistributionandwallshearstress.Theresultsofthisstudysupporttheviewthatthenon-planarityofbloodvesselsandthenon-Newtonianpropertiesofbloodareofimportantinhemodynamicsandplayasignificantroleinvascularbiologyandpathophysiology.