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

简介：Depositionofamorphousparticles,asaprevalentproblemparticularlyinthespraydryingoffruitandvegetablejuices,isduetolow-molecular-weightsugarsandisstronglydependentontheconditionoftheparticlesuponcollisionwiththedryerwall.Thispaperinvestigatestheconditionoftheamorphousparticlesimpactingthewallatdifferentdryingconditionswiththeaimofelucidatingthedepositionmechanismandphysicalphenomenainthedryingchamber.Amodelsucrose-maltodextrinsolutionwasusedtorepresentthelow-molecular-weightsugar.Particledepositswerecollectedonsamplingplatesplacedinsidethedryerforanalysesofmoisturecontent,particlerigidity(usingSEM)andsizedistribution.Moisturecontentwasadoptedasageneralindicatorofstickiness.Productparticlescollectedatthebottomoftheexperimentaldryerwerefoundtohavehighermoisturethanparticledepositsonsamplersinsidethedryer.Moisturecontentprofileinthedryershowsthatapartfromtheatomizerregion,whereparticlesarerelativelywet,particledepositsatotherregionsexhibitsimilarlowermoisturecontent.Atthehighesttemperatureadoptedintheexperiments,particlesbecamerubberysuggestingliquid-bridgeformationasthedominantdepositionmechanism.Furtheranalysisonparticlessizedistributionrevealsaparticlesegregationmechanismwherebysmallerparticlesfollowpreferentiallytothecentralairstreamwhilelargerparticlestendtore-circulateinthechamber,aspredictedinpastCFDsimulation.ThefindingsfromthisworkwillformthebasisandprovidevalidatingdataforfurthermodelingofwalldepositionofamorphousparticlesinspraydryingusingCFD.

简介：Inthispaper,anewmethodoftopologicalcleanupforquadrilateralmeshispresented.Themethodfirstselectsapatchofmesharoundanirregularnode.Itthenseeksthebestconnectionoftheselectedpatchaccordingtoitsirregularvalenceusinganewtopologicaloperation:smallpolygonreconnection(SPR).Byreplacingtheoriginalpatchwithanoptimalonethathaslessirregularvalence,meshqualitycanbeimproved.Threeapplicationsbasedontheproposedapproachareenumerated:(1)improvingthequalityofaquadrilateralmesh,(2)convertingatriangularmeshtoaquadrilateralone,and(3)adaptingatrianglegeneratortoaquadrilateralone.Thepresentedmethodishighlyeffectiveinallthreeapplications.

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.