CFD High Lift Prediction Workshop
Case3ResultsVerificationExercise
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compiledbytheHiLiftPW Committee
AIAAHiLiftPW-3- Denver,CO,USAJune3-4,2017
CFD High Lift Prediction Workshop
Overview• SourcesofdifferencesbetweenCFDresults(assuminguse
ofthecorrectgeometry):– Differentequations
• Thismaybeaduetounintentionalbugsinthesoftware• Oritmaybeonpurpose(e.g.,tweaktoaturbulencemodel)
– Useofdifferentboundaryconditions– Insufficientgridrefinement– VERIFICATION canhelpdiagnosethis
• Strongverification:methodofmanufacturedsolutions(MMS)• Weakverification:TurbulenceModelResource(TMR)website(https://turbmodels.larc.nasa.gov)
• Wewillshowyou:manyofthecodesusedinthisworkshophavenotbeenverified
• Wewillattempttolinkinconsistenciesintheverificationcasetoinconsistenciesinthelargehigh-liftcases
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CFD High Lift Prediction Workshop
Case3– 2DAirfoilNear-WakeVerification
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• Studyasimple2-Dcaseofnear-wakebehindDSMA661(MODELA)airfoil(J.FluidMech.(1985),Vol.160,pp.155-179)fromTMRwebsite
• CompareCFDresults that useostensibly thesame turbulence model toeach other• ForSAandSST,consistent results from2codes aretaken fromtheTMRwebsite• Results foragiven turbulence modelshould beconsistent as thegrid is refined
Notepossibleissue:farfield BCextentofonly20cmeansthatsolutiondifferencesmayoccurbecauseofnon-identicalfarfield BCimplementations
AIAAHiLiftPW-3- Denver,CO,USAJune3-4,2017
CFD High Lift Prediction Workshop
OverallresultsforCase3
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Red:SA-typemodelsGreen:SST-typemodelsBlue:Othermodels
AIAAHiLiftPW-3- Denver,CO,USAJune3-4,2017
LiftandDrag
CFD High Lift Prediction Workshop
OverallresultsforCase3
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Red:SA-typemodelsGreen:SST-typemodelsBlue:Othermodels
AIAAHiLiftPW-3- Denver,CO,USAJune3-4,2017
Minu-velocityinthewake
CFD High Lift Prediction Workshop
SAmodel
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CFD High Lift Prediction Workshop
SA– referencesolutions
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CFD High Lift Prediction Workshop
IdentifySAresultsthatareconsistent
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CFD High Lift Prediction Workshop
PID Plot letter CL CD Velmin 1.01 Velmin 1.80 Overall001.1 A No No No No No003.2 C Y Y close No No004.1 D Y Y Y Y Y004.4 D close Y close Y close006.2 F Y Y Y Y Y007.1 G Y Y Y Y Y008.1 H Y close close Y close010.1 J close Y No Y No012.1 L Y Y (missing) (missing) Y015.1 O close close (missing) (missing) close016.2 P close close Y No No018.1 R No No No No No019.1 S No No No No No021.1 U Y No No No No022.2 V Y Y Y Y Y023.3 W Y Y Y Y Y026.1&3 Z close Y Y Y close026.2&4 Z Y Y Y Y Y030.5 b No No No No No033.2 f Y No No No No034.1 g close No No No No035.1 h No No No No No036.5 m Y Y No Y No 9AIAAHiLiftPW-3- Denver,CO,USAJune3-4,2017
CFD High Lift Prediction Workshop
OverallsummaryfortheSAmodel• SAresultsincludeSA,SA-neg,SA-noft2,andSA-QCR– NotincludingRorRCvariantshere
• Consistentwitheachother:– CFL3D,FUN3D,004.1,006.2,007.1,012.1,022.2,023.3,026.2/4…30%ofentries
• Fairly“close”,butnotfullyconsistent:– 004.4,008.1,015.1,026.1/3
• Not-so-close:– 001.1,003.2,010.1,016.2,018.1,019.1,021.1,030.5,033.2,034.1,035.1,036.5• Note:036.5wasconsistenton3outof4measures
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CFD High Lift Prediction Workshop
Lookatconsistent SAresultsinwake
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CFD High Lift Prediction Workshop
Cross-correlationwithHighLiftCases
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SAonly(therewerenotenoughresultsfromothermodelstodrawconclusions)
Note:someranCase3butdidnotrunhighliftcaseswiththesamemodel(only
plottingthosewhodid)
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CFD High Lift Prediction Workshop
HL-CRM,alpha=8deg.
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AllSAResults
CL CD Cm
AIAAHiLiftPW-3- Denver,CO,USAJune3-4,2017
CFD High Lift Prediction Workshop
HL-CRM,alpha=8deg.
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AllSAResults
ResultscorrespondingwiththemostconsistentSAsolns fromCase3
CL CD Cm
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CFD High Lift Prediction Workshop
HL-CRM,alpha=16deg.
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AllSAResults
CL CD Cm
AIAAHiLiftPW-3- Denver,CO,USAJune3-4,2017
CFD High Lift Prediction Workshop
HL-CRM,alpha=16deg.
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AllSAResults
CL CD Cm
ResultscorrespondingwiththemostconsistentSAsolns fromCase3
AIAAHiLiftPW-3- Denver,CO,USAJune3-4,2017
CFD High Lift Prediction Workshop
JSM,nonacelle/pylon
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AllSAResultsResultscorrespondingwiththemost
consistentSAsolns fromCase3
NoconsistencynearCL,max
AIAAHiLiftPW-3- Denver,CO,USAJune3-4,2017
CFD High Lift Prediction Workshop
Othermodels• SSTresults– Hadfarlesscontributions– Couldnot notetrendswithhigh-liftcases– ThreeresultswereconsistentwithCFL3D&FUN3Dcase3referencesolution:• 010.2,016.3,023.4• Others(003.1,020.3,025.1,030.6,036.6)wereclose,butlessconsistent– Note:020.3 usedSST+SAS,025.1 usedSST-V-sust,036.6 usedSST(mod)
• SSG/LRR-RSM-w2012– Twocontributors(onlyoneranhighliftcases)– 026.6 wasreasonablyconsistentwithCFL3D(026.5 wasoffonCL)
– 016.1 wasnotconsistentforumin atx/c=1.8
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CFD High Lift Prediction Workshop
Conclusions
• SimilartopreviousverificationexercisesfrompastDPWsandHiLiftPWs:– Ifacodehasnotbeenverified,thenyoucannotexpecttogetconsistentsolutionswithothercodes
• Only30%ofparticipantswhoranCase3withSAwerefullyconsistent
• TakingthePIDsthatproducedthemostconsistentCase3results(withSA):– TheirSAresultsalsoweregenerallymoreconsistentforthetwoHL-CRMcases
– ButtheywerenotconsistentforJSMnearCL,max• nogridstudy
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CFD High Lift Prediction Workshop
Backupslides
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CFD High Lift Prediction Workshop
SampleiterativeconvergenceresultsforCase3
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(onfinegrid)
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CFD High Lift Prediction Workshop
Definea“bandofacceptability”
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(ash->0)
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CFD High Lift Prediction Workshop
FocusonSA(CL)
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Zoom:
CFD High Lift Prediction Workshop
FocusonSA(CD)
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Zoom:
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CFD High Lift Prediction Workshop
FocusonSA(umin atx/c=1.01)
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Zoom:
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CFD High Lift Prediction Workshop
FocusonSA(umin atx/c=1.80)
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Zoom:
AIAAHiLiftPW-3- Denver,CO,USAJune3-4,2017
CFD High Lift Prediction Workshop
OtherSA-relateditemsofnote
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• RorRCappearstolowerCL andCD somewhat(comparedtoSA),butthereisnotenoughconsistencyfromtheresultstoknowforsure
AIAAHiLiftPW-3- Denver,CO,USAJune3-4,2017
CFD High Lift Prediction Workshop
OtherSA-relateditemsofnote
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• UseoflowMpreconditioningchangesresults
AIAAHiLiftPW-3- Denver,CO,USAJune3-4,2017
CFD High Lift Prediction Workshop
OtherSA-relateditemsofnote
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• In026,aFarfield PointVortex(ffpv)wasrequiredtobringCL inlinewith“accepted”solutions• Reasonforthisisnotknown• Thereferencesolutionsdidnot useffpv
• Thenoft2optionhadasmalleffectondrag(reasonunknown)AIAAHiLiftPW-3- Denver,CO,USAJune3-4,2017
CFD High Lift Prediction Workshop
OtherSA-relateditemsofnote
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• Adaptinggoestosameresultasstandardgridrefinement
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CFD High Lift Prediction Workshop
LookatconsistentSAresultsinwake
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CFD High Lift Prediction Workshop
SurfaceCp resultsforCase3
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Surfacepressurecoefficientsdonottellustoomuch
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CFD High Lift Prediction Workshop
Velocityprofiles
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CFD High Lift Prediction Workshop
Velocityprofiles
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CFD High Lift Prediction Workshop
Turbulentshearstressprofiles
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CFD High Lift Prediction Workshop
Turbulentshearstressprofiles
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CFD High Lift Prediction Workshop
SSTmodel
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CFD High Lift Prediction Workshop
FocusonSST(CL)
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CFD High Lift Prediction Workshop
FocusonSST(CD)
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CFD High Lift Prediction Workshop
FocusonSST(umin atx/c=1.01)
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CFD High Lift Prediction Workshop
FocusonSST(umin atx/c=1.80)
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CFD High Lift Prediction Workshop
SSTmodelsfromcase1a
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alpha=8deg. alpha=16deg.
CFD High Lift Prediction Workshop
SSG/LRR-RSMmodel
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CFD High Lift Prediction Workshop
FocusonRSM(CL)
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CFL3Dwasrunforcomparisontothe2submittedresults
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CFD High Lift Prediction Workshop
FocusonRSM(CD)
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CFD High Lift Prediction Workshop
FocusonRSM(umin atx/c=1.01)
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CFD High Lift Prediction Workshop
FocusonRSM(umin atx/c=1.80)
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