简介：Anumericalsimulationisperformedtofindoutakeyvorticalstructureinthelaminar-turbulenttransition.Alow-speedstreakisgeneratedinsidealaminarboundarylayerusinganisolatedcuboidroughness,aimedatprovidinganenvironmentunstabletoouterdisturbances.Then,ashortdurationjetisissuedintotheboundarylayer.Whenthejetvelocityislow,somevorticesappearintheboundarylayer,butthetransitionoftheboundarylayerdoesnottakeplace.However,whenthejetvelocityexceedsacertainthreshold,twovorticesnewlyappearabovetheelongatedlegsofaV-shapedvortexandonlyoneofthemisstretchedandsurvives.Afterthat,vorticesaregeneratedoneafteranotheraroundthesurvivedone.Bycomparingthedecayedandthesurvivedvortices,itisfoundthatthedifferenceintheirheightsisthekeycharacteristicwhichleadstothetransition.

简介：Thepulsed-sprayfluid-bedgranulation(PSFBG)processwasinvestigatedandoptimizedusingdefinitivescreeningdesign,arecentlyproposednewclassofthree-leveldesignofexperimentmethod.Suchadesignenabledquadraticmodelstobeestablishedthatdescribedtheeffectofsixinputprocessparameters-inletairtemperature,inletairhumidity,bindersprayrate,atomizationpressure,pulseperiod,andpulsewidth-onthegranulequalityinaPSFBGprocess.Mathematicalmodelsofthemeanparticlesize,relativesizedistributionwidth,productionyield,andporosityweredevelopedtoquantifytherelationshipsbetweentheinfluencingfactorsandcriticalqualityattributes.Onthebasisofconstraintsonthedesiredgranuleproperties,adesignspaceforPSFBGwasdeterminedandrangesoftheoperatingparametersweredefined.Anacceptabledegreeofpredictionwasconfirmedbyvalidationexperiments,demonstratingthereliabilityandeffectivenessofusingdefinitivescreeningdesigntostudythePSFBGprocess.Thismethodcanacceleratescreeningandoptimizationofthisprocesswithinalargemultidimensionaldesignspace.