Flotherm 教程 Build, Solve and Analyse a sample case.ppt

Lecture2A Build SolveandAnalyseaSimpleCase 2 52 Fivestepstobuildamodel Step1 DefinewhattomodelStep2 CreategeometryStep3 AddgridStep4 SolvethemodelStep5 Analysetheresults 3 52 Definewhattomodel StartSimple ElectronicsBox ChassisModelwithanenclosure ComponentsModelwithaheatsource VentsModelwithperforatedplates 4 52 Save Load Beforebuilding saveprojectProject SaveChoosesolutiondirectoryEnterprojectnameToloadexistingprojectProject LoadChoosesolutiondirectorySelectprojectfromlist SavingprojectsTosavethecurrentproject useProject Saveorthesaveicon Thisoverwritesthecurrentprojectondisk Itsavesthefullprojectdatasettotheprojectsdirectory Notethatiftheprojecthasneverbeensavedorwasoriginallysavedbyanotheruser theSaveProjectDialogisdisplayedsothatyoucanidentifytheappropriateprojectname directoryandotherancillaryinformation Tosavethecurrentprojectunderanewname useProject SaveAs ThiswilllaunchtheProjectSaveDialog ProjectSaveDialogProjectNameSetsthenametheprojectdatasetistobesavedunder Theprojectnameappearsinthestatusbarnearthebottomoftheapplicationwindow Ifyouenterthenameofanexistingprojectyouwillbepromptedtoconfirmthesavewhichwilloverwritethenamedproject ClassIdentifiestheprojectclasstype e g departmentname Sub ClassIdentifiestheprojectsub classtype e g clientname TitleSetstheprojecttitleintendedtolaterhelpidentifytheproject Thetitlefortheactiveprojectalwaysappearsinthestatusbarnearthebottomofthewindow Notes CallstheEditNotesDialogtoattachreferenceinformationtotheproject ProjectSolutionDirectoryIndicatesthedirectorytoholdtheprojectdataandresults Tochangethedirectory click Browse todisplayafilebrowsertochoosetherequireddirectory SaveAsTemplateRequeststheprojectissavedasatemplateandassignedtotheCategoryindicated YoucanchangethisCategorybyeitherchoosingitfromthepop uplistortypinginyourown LoadingProjectsToloadanexistingprojectintotheprojectmanager useProject Load ThiswilllaunchtheProjectLoadDialog ProjectLoadDialogTheProjectLoadDialogcomprisesalistofalltheprojectsoftheclassificationselectedintheFilterProjectdialog Bydefault thelistisfilteredbyyourusername Toloadaproject selectitinthelistandclick Load Tohelpyoucheckyouhaveselectedtherightproject theprojecttitleappearsbelowthelist andusing Notes youcandisplayanyattachedprojectnotes Filter CallstheFilterProjectdialogtoallowyoutoconfinethescrolllisttoparticularcategoriesofprojectfiles i e byclass sub class username beforedateorafterdate Delete Removestheselectedprojectanditsrelatedsolutiondatafromthelistandthecurrentprojectdirectory Youcannotdeleteaprojectwhileitiscurrentlyloadedinprogrammemory Ifyouwanttodeletethecurrentproject youwillhavetoeitherloadinadifferentprojectorstartanewonefirst Also youcannotdeleteaprojectthatwasnotsavedunderyourownusername Unlock Allowsyoutounlockaprojectafterasystemfailure But asFLOTHERMalsolocksprojectsincurrentuse beforeunlockingaprojectcheckthatyouarenotusingitinanotherprogramsession andinamulti usersystem itisnotbeingusedbysomeoneelse Pack CallsthePackProjectselectiondialogtosavethehighlightedprojectinacompressedformatofbothmodelandsolutiondatareadyforarchivingortransfertoFlomericscustomersupport Youchoosethefilenameanddestinationwiththedefaultfileextensionbeing pack Note AsFLOTHERMidentifiespackedprojectsbythe packfilenameextension whennamingthepackedprojectensureyoukeepthedefault packextension Unpack CallstheUnpackProjectselectiondialogsothatyoucanchooseapackedfile seePackabove andimportintothesystem Bydefault thefiltersearchesfor packfiles Whenunpacked thenameoftheprojectisaddedtothescrolllist Astheprojectnamemaynotbethesameasitsoriginalfilename theimportedunpackedprojectishighlightedbyacoloredbackground Note Youcannotunpackaprojectintothesameprojectdirectorythatitwaspackedfromduetoconflictsbetweenthetwoprojects Youmustfirstdeletetheoriginalprojectbeforeunpackingthepackedversion orchangetheProjectSolutionDirectorysetting TitleDisplaysthetitleoftheprojectcurrentlyhighlightedinthescrolllist ProjectLoadDialog cont ProjectSolutionDirectorySetsthedirectoryfromwhichtoloadyourprojects Theinitialdefaultsettingisset upduringtheinstallationprocedure Usethe Browse buttontocallafilebrowsertolocatethedirectory Anychangemadehereisresetifthedialogiscancelled Tosavetheprojectinanotherdirectory youmustusetheProjectSavedialog Project SaveAs Catalog CatalogsalltheFLOTHERMprojectsheldinthesolutionsub directoryanddisplaystheminthedialogselectionlist Use Catalog whenitisknownthatthereareprojectscopiedormovedintothedirectoryusingtheoperatingsystem buttheyarenotlistedinthedialog Alternatively usethekeysequencewiththeProjectManageropen beforecallingtheLoadProjectDialog Notes CallstheNotesdialogtodisplayanynotesattachedtotheprojectcurrentlyhighlightedinthescrolllist Load Loadstheprojectselectedintheprojectlist Cancel Cancelstheloadandanysolutiondirectoryselectionchange Importing ExportingProjectscanbeimportedandexportedtosharewithotherusers ThePDMLfilecontainsalltheprojectinformation butdoesnotcontainanyresults Export Right Clickontheprojectnameatthetopoftheprojectmanagertree thenchooseExport ChooseFlomericsFile thenPDML Import Right Clickontheprojectnameatthetopoftheprojectmanagertree thenchooseImport ChooseFlomericsFile thenPDML 11 52 HowdoIcreategeometry SelectappropriateitemSetitssizePositionitcorrectlyDefinethematerial 12 52 ChassisStructure Tomodelahollowbox usetheEnclosureSmartPartSelectEnclosurefromthePMgeometrypalette defaultenclosureiscreatedSelectEnclosureintheDBgeometrypalette nowdrawtheenclosure 13 52 SettingSize SelectEnclosureRight ClicktoactivateEnclosureMenuSelectConstructionTypeappropriatesizeTypeappropriatethicknessWallscanbethin collapsed orthick non collapsed 14 52 SettingLocation SelectEnclosureRight ClicktoactivateEnclosureMenuSelectLocationTypeappropriatelocation 15 52 SettingSize Location Alternatively sizeandlocationcanbesetinDBSelecttheEnclosureMovehandlestoresizeMoveEnclosuretoreposition MoveobjectRe sizeinonedirectionRe sizeintwodirections EnclosureSmartPartIt spossibletobuildaboxusingcuboids butit sbettertousetheenclosuresmartpart Theenclosuresmartpartconsistsofahollowcuboid shapedboxwithsixsolidwalls eachofwhichcanbe OptionallyremovedTreatedasthickorthinHoledbyoneormoreresistancesorothermaterialsTheEnclosureDialogsetsthebasicspecificationfortheenclosure thatis itsoverallsizeandthicknessofallthewalls Butforsettingtheindividualsidedetails e g itsexistenceordifferentthickness theSideofEnclosureDialogisused SizingtheEnclosureSmartPartSetthesizeoftheenclosurebyright clickingontheenclosure thenselectingConstruction Alternatively resizetheenclosureintheDrawingBoard PositioningtheEnclosureSmartPartPositiontheenclosurebyright clickingontheenclosure thenselectingLocation Alternatively movetheenclosureintheDrawingBoard 18 52 AttachingMaterial OpenLibraryManagerSelectMaterialDragitontoEnclosureOr Right ClickonEnclosureSelectMaterialAttachMaterialfromList 19 52 AttachingMaterial ToviewMaterialpropertiesRight ClickonEnclosureSelectMaterialSelecttheattachedmaterialfromlistClickEdit MaterialThethermalandelectromagneticpropertiesofanobjectarecontrolledbythematerialattributeattachedtoit ThematerialpropertiescanbeviewedandeditedintheMaterialPropertyDialog Themostsignificantthermalpropertyistheconductivity whichsetsthethermalconductivityforthematerialaccordingtothreeoptions iConstant Setsaconstantvalueforallthreedirections iiTemperatureDependentConductivity Setstheconductivitytovaryaccordingtoalinearfunctionoftemperature Conductivity Value Coeff Temperature ReferenceTemperature wheretheValueyouenteristheconductivityattheReferenceTemperatureandTemperatureisthetemperatureofthesolidmaterial iiiOrthotropicConductivity Setstheconductivityvaluesseparatelyineachdirectionforthematerial ThisoptionallowsyoutodefinedifferentconductivityvaluesinthethreecoordinatedirectionsofX YandZDensityandSpecificHeatarerequiredforTransientsimulations 21 52 HowdoIaddheat Selectappropriateitem Source SetitssizePositionitcorrectlyDefinethepower SourceAttribute 22 52 SettingSize Location SelectSourceRight ClicktoactivateSourceMenuSelectLocationAlternatively sizeandlocationcanbesetinDB 23 52 AddingPower SelectSourceRight ClicktoactivateSourceMenuSelectSourceCreateNewSourceAttachSourcefromList 24 52 AddingPower SourcePoweriscontrolledbytheSourceAttributeForathermalsource chooseAppliesTo TemperatureSetthePower SourceActivateActivatesthedialogoptions Whende activated theeffectsofthesourceareremoved Bydefault allsourcesarede activated Source VolumeOnlyactiveforvolumesources For temperature thisoptionsetsthesource positive orsink negative ofheatperunitvolume Source AreaOnlyactiveforplanarsources For temperature thisoptionsetsthesource positive orsink negative ofheatperunitareaoftheplane TotalSourceOptionFor temperature thisoptionsetsthetotalsourceofheatappliedoverthedefinedplaneorvolumewhichtheprogramwilldistributeuniformlyovertheplaneorvolume FixedValueOptionFor temperature thisoptionfixesthetemperaturestothesetvalue Ifitisaplanarsource thenthetemperatureissetinthecellsadjoiningtheplaneontheselectedsideoftheplane Thefigurebelowisanexampleofhighsideattachments LinearSourceOption forTemperature For temperature thelinearsourceofheatperunitareaoftheplanarregionisgivenby foreachgridcellonthehighside source coefficientx value temperature wheretemperatureisthatinthegridcellinthefluidonthehighside Theprogramcalculatestemperature whereastheusersetscoefficientandvalue TransientAttribute Onlyavailablefortransientsimulations Itallowsyoutoapplyatransientfunctiondescribingthevariationofthesourceoutputwithtime Pressing TransientAttribute resultsinthedisplayoftheTransientFunctionAttributeDialogsoyoucaneitherselectanexistingtransientfunctionorcreateanewone 26 52 HowdoIaddvents Selectappropriateitem PerforatedPlateSP SetitssizePositionitcorrectlyDefinethelosscoefficient 27 52 SettingSize SelectPerforatedPlateRight ClicktoactivatePerforatedPlateMenuSelectConstructionTypeappropriatesize 28 52 SettingLocation SelectPerforatedPlateRight ClicktoactivatePerforatedPlateMenuSelectLocationTypeappropriateposition 29 52 SettingSize Location Alternatively sizeandlocationcanbesetinDBSelectthePerforatedPlateMovehandlestoresizeMovePerforatedPlatetoreposition MoveobjectRe sizeinonedirectionRe sizeintwodirections 30 52 SettingLossCoefficient ThepressuredropcharacteristicsofthePerforatedPlatearesetintheConstructionDialogEnteraholepatternOrenterafreearearatioChooseResistanceModel PerforatedPlateSmartPartHoleTypeandSizeSetstheshapeandsizeofthehole Youcanhavesquare roundorhexagonalholes Theholeswillcutthroughthefullthicknessoftheplate CoverageDefinesthefreearearatio theratiooftheholestothetotalareaacrosstheplate Bydefault theprogramcalculatesthefreearearatiofromthepatternofholesspecified Thepitchsetsthespacingbetweentheobjects Itisthedistancebetweenthestartedgesofeachobjectinthegivendirection Alternatively youcanenterthefreearearatiodirectly ResistanceModelSetstheresistancemodeltooneofthreeoptions StandardThisoptionshouldbeusedwhenyouknowthelosscoefficientforthisparticularperforatedplateandtheflowisfullyturbulent AdvancedThisoptionshouldbeusedwhenyouknowthelosscoefficientforthisperforatedplateandtheflowistransitionalorlaminar AutomaticThisoptionautomaticallyselectsthecorrectcoefficientsintheresistanceformulabasedonthefreeareratioprovidedbytheholecalculationormanualsettinginthedialog Youneedtospecifytheflowregime Low IntermediateorHighVelocity asdifferentcoefficientsarerequiredforeachregime TheregimesaredefinedbytheReynoldsnumberoftheflowthroughtheholes LowVelocityforlaminarflowsRe1e5 StraightenFlowSetsthetwoairvelocitycomponentsparalleltotheplateoneitheritshighorlowside asindicatedbythecheckedbox tozero Thefigurebelowshowstheflowstraightenedforthehighsideoftheplate 32 52 DefineGrid Whatisgrid ThesolutiondomainissplitintoanumberoffinitevolumesTheequationsaresolvedateachcell 33 52 DefineGrid Whydoweneedgrid AllowsequationstobesolvedatdiscretepointsMoregrid morepointstocaptureoverallpicture morepreciseresults GridDefinitionThefinerthegridused i e thegreaterthenumberofgridcells thecloserthealgebraicequationsapproximatetothedifferentialequationsfromwhichtheyoriginated Normallymoregridisusedinregionsofthedomainwheregradientsofthevariablesareexpectedtobegreatest However grid independenceofthesolutionaloneisnotenoughtoensurethatthesolutionobtainedsimulateswhatinrealityoccursbecauseothermodelingassumptions e g theaccuracyoftheboundaryconditioninformationsupplied theadequacyoftheturbulencemodel maybedeterminingfactorsintheagreementofthesimulationwithphysicalreality Consequently theoutcomeofaCFDsimulationmustbeinspectedcarefullywithaviewtoassessingthephysicalrealismoftheresultsobtained Lecture5describesgriddingtechniquesinmoredetail 35 52 RefiningGrid Whydoweneedgrid Aswerefinethegrid moredetailisapparent 36 52 DefineGrid Howdoweaddgrid Geometryprovideskeypointsforgrid Gridlinesautomaticallyappearalongedgesofallobjects 37 52 DefineGrid Howdoweaddgrid Gridcanbegeneratedautomaticallytofourdefaultlevels N B None Keypointgrid 38 52 DefineGrid Howdoweaddgrid 39 52 Solving GoverningequationsaresolvedwithindomainAttachambientstodescribeconditionsoutsidethedomain 40 52 AmbientConditions Right ClickontheSystemNodeSelectAmbientsCreateAmbientAttributeAttachAmbienttoSystem AmbientConditionsBydefault theambientconditionsarethosesetintheGlobalSystemSettingsDialog thatis thedatumpressure fluidtemperatureandtemperatureofaremoteradiatingsource Theambientconditionscanbefurtherrefinedforaparticularfaceofthesolutiondomainbyattachinganambientattribute AmbientattributesaredefinedusingtheAmbientAttributeDialogName IdentifiestheambientattributesGaugePressure Setsthepressureforthefluidexternaltothedomainface relativetotheDatumPressure Temperature Setsthetemperatureforthefluidexternaltotheselecteddomainface RadiantTemperature Setsthetemperatureofaremoteradiatingsource HeatTransferCoefficient SetstheHeatTransferCoefficientforanysolidsurfacescoincidentwiththeselecteddomainface IfyouareusingtheKEturbulencemodel youcanalsosetTurbulentKineticEnergyandTurbulentDissipationRate ExternalVelocity Setstheambientwindvelocityforthefluidexternaltotheselecteddomainorcutoutface 42 52 Solving ThegoverningequationsaresolvediterativelyErrorinsystemismeasuredWhenthiserrorislowenough resultscanbeaccepted 43 52 AnalyzeResults ViewPlanesTemperatureplaneVelocityplane Lecture2B Build SolveandAnalyseaSimpleCase 45 52 Whattypeofresultdowewant Whattypeofresultswerewetryingtoget Arewelookingforgeneralairflow boardtemperatures orjunctiontemperatures Togetthoseresults whydidwemodeltheChassis ventsandtotalpower Initially wewereonlylookingforgeneralairflowthroughthevents andtemperaturerise 46 52 Wasthegridsufficient Wasthegridsufficienttogetaccurateairflowresults Whatairflowpatternwasimportanttocapture Thegridwassufficienttocapturetheairflowturningfromhorizontalflowtoverticalflow 47 52 HowdidwechoosetheSystemsize ThesystemsizeuseddependsonwhethertheuserwishestomodeltheairflowoutsideoftheChassis Ifnot thesystemsizeissettoth