hpcmo reno02 - Cobalt Solutions, LLC

1 AIAA 2002 1021 Progress on Detached-EddySimulation of Massively SeparatedFlowsKyle D. SquiresMAE Department, Arizona State UniversityJames R. Forsythe and Scott A. MortonDept. of Aeronautics, USAF AcademyWilliam Z. Strang, Kenneth E. Wurtzler, and Robert Solution, LLCM atthew J. GrismerAir Force Research LaboratoryPhilippe R. SpalartBoeing Commercial AirplanesAerospace Sciences Meeting 200214 18 January 2002 / Reno, NevadaFor permission to copy or republish, contact the American Institute of Aeronautics and Astronautics1801 Alexander Bell Drive, Suite 500, Reston, VA 20191 MAED epartment, , , {, , ,Spalartetal.[2]proposedDetached-EddySim ulation(DES) ,combiningReynolds-averagedNavierStokes( RANS)andLargeEddySimulation(LES).DEScomb inesthee ,moreunsteady ,\AnalysisofFullAircraftwithMassiveSepar ationUsingDetached-EddySimulation".Numer ous owsareexamined,includingacylinder,two-an dthree-dimensionalforebodies,aprolatesph eroid,asupersonicbase ow,adeltawing,anotionaltruck,theC130,the F-16, owsolver{ Cobalt {whichusesMessagePassingI nterface(MPI) ,solutionsareobtainedonasmanyas512proces sors,providingfullaircraft, ow eldsencounteredinDoDap-plicationsoccurwi thinandaroundcomplexde-vicesandatspeedsf orwhichtheunderlyingstateofthe (CFD)isgainingincreasedpromi-nenceasause fulapproachtoanalyzeandultimatelydesignc on gurations,e cientandaccuratesolutionsrequiresubstant iale ,numericalsolutionoftheNavier-Stokesequa tions,ande cient Professor,MemberofAIAAyAssistantProfesso r,MemberofAIAAzAssociateProfessor,Associ ateFellowofAIAAxPresident,MemberofAIAA{V icePresident,MemberofAIAAkVicePresident, MemberofAIAA Engineer, ,CFDhasremainedlimitedasareliabletoolfor predictionofinherentlyunsteady owsat owsarebasedonsolutionoftheReynolds-avera gedNavier-Stokes(RANS)}}}}

2 Owswithnoregionsofreversed ow,orpossiblyexhibitingshallowseparation s,itappearsinevitablethatRANS turbulencemodelsareunabletoaccuratelypre dictphenomenadominating ,arguably,arewhatdefeatsRANStur-bulencem odels, {1021 Toovercomethede cienciesofRANS modelsforpredictingmassivelyseparated ows,Spalartetal.[2]proposedDetached-Eddy Simulation(DES)withtheobjectiveofdevelop inganumericallyfeasibleandaccurateapproa chcombiningthemostfavor-ableelementsofRA NS modelsandLargeEddySim-ulation(LES).Thepr imaryadvantageofDESisthatitcanbeapplieda thighReynoldsnumbersascanReynolds-averag edtechniques,butalsoresolvesgeometry-dep endent, owsincomplexcon gurations, (DoD)Chal-lengeprojectbytheHighPerforman ceComputingModernizationO ce( hpcmo ), rstyeare ortontheChallengeproject{\AnalysisofFull AircraftwithMassiveSeparationUsingDetach ed-EddySimulation".Duetothelargescopeoft heproject,onlybriefsummariesofthevar-iou scalculationsthathavebeenundertakenwillb eprovided, ortisCobalt60(Strangetal.)}}

3 [6]) {acompressible owsolverdevelopedattheAirForceResearchLa boratoryinsupportoftheCom-monHighPerform anceSoftwareSupportInitiative(CHSSI).The relevantimprovementsavailableinthecommer cialversionandcentraltothesuccessofthisp roposalarerigidbodymotion,fasterper-iter ationtimes,theinclusionofSST-basedDES,im provedtrip-ping,abilitytocalculatetime-a veragesandturbulentstatistics,animproved spatialoperator, [6]validatedthecodeonanumberofproblems,i ncludingtheSpalart-Allmarasmodel(whichfo rmsthecoreoftheDESmodel).Tomaroetal.[7]c onvertedCobalt60fromexplicittoimplicitti meintegration, [8]thenparallelizedthecode, [5] [9],Karypisetal.[10] (SA)one-equationmodel[12]solvesasinglepa rtialdi erentialequationforavari-ablee erentialequationisderivedby\usingempiric ismandargumentsofdimensionalanalysis,Gal ileanin-varianceandselecteddependenceont hemolecularviscosity."[1]Themodelinclude sawalldestructiontermthatreducestheturbu lentviscosityintheloglayerandlaminarsubl ayerandtriptermsthatpro-videsasmoothtran sitionfromlaminartoturbulent , ,atransportequationisusedtocomputeaworki ngvariableusedtoformtheturbulenteddyvisc osity,De Dt=cb1[1 ft2]eSe hcw1fw cb1 2ft2i e d 2+1 hr (( +e )re )+cb2(re )2i;+ft1 U2;(1)wheree tisobtainedfrom, t=e fv1;fv1= 3 3+c3v1; e ;(2)where ,eS fv3S+e 2d2fv2;(3)fv2= 1+ cv2 3;(4)fv3=(1+ fv1)(1 fv2) ;(5) (3)di ersfromthatdevelopedinSpalartandAllmaras [12]viatheintroductionoffv3andre-de owsandhavetheadvantagethatforsimulationo f owswithlaminarseparation,spuriousupstrea mpropagationoftheeddyviscosityintoattach ed, cationwascrucialforsuccessfulsimulationo fthe ,fw=g 1+c6w3g6+c6w3 ;1=6g=r+cw2(r6 r).}

4 R e eS 2d2:(6)Thefunctionft2isde nedas,ft2=ct3exp( ct4 2):(7)2of9 AmericanInstituteofAeronauticsandAstrona uticsPaper2002{1021 Thetripfunctionft1isspeci edintermsofthedis-tancedtfromthe eldpointtothetrip,thewallvorticity!tatth etrip,and Uwhichisthedi er-encebetweenthevelocityatthe eldpointandthatatthetrip,ft1=ct1gtexp ct2!2t U2 d2+g2td2t ;(8)wheregt=min(0:1; U=!t x)and :1355, =2=3,cb2=0:622, =0:41,cw1=cb1= 2+(1+cb2)= ,cw2=0:3,cw3=2,cv1=7:1,cv2=5,ct1=1,ct2=2 ,ct3=1:1,andct4= cationtotheSpalart-AllmarasRANS model[12]suchthatthemodelreducestoitsRAN S formulationnearsolidsur-facesandtoasubgr idmodelawayfromthewall[2]. ,d,byed,whereedisde nedas,ed min(d;CDES ):(9)InEqn.(9),forthecomputationsperform edinthisproject, isthelargestdistancebetweenthecellcenter underconsiderationandthecellcenterofthen eighbors( ,thosecellssharingafacewiththecellinques tion).In\natural"applicationsofDES,thewa ll-parallelgridspacings( ,streamwiseandspanwise)areatleastontheor deroftheboundarylayerthick-nessandtheS-A RANS modelisretainedthroughouttheboundarylaye r, ,ed= ,pre-dictionofboundarylayerseparationisd eterminedinthe`RANS mode' , ,thelengthscaleed=CDES intheLESregionyieldsaSmagorinskyeddyvisc ositye /S ,theroleof istoallowtheenergycascadedowntothegridsi ze;roughly,itmakesthepseudo-Kolmogorovle ngthscale,basedontheeddyviscosity, :65wassetinhomogeneousturbulence[3].}

5 Strelets[4]introducedaDESmodelbasedonMen ter'sShearStressTransportmodel[13] owsthathavebeencomputedduringthe ,assessment,andimprovementofarelativelyn ewcomputationaltechniqueforpredictingtur bulent owssuchasDetached-EddySimulationisthebui ldingofanexperiencebasethatcanbeusedtopr ovideinsightandexperienceusefulforaddres singpotentialprob-lemsandguidingthesucce ssoffuturee ortsasthemethodisappliedtonewcon owssummarizedbelowpossesseselementsthath avebeenvaluableinadvanc-ingthecomputatio nalapproachandimprovingDEScapabilitiesfo rengineeringandscienti ,takingadvantageofthereasonablerangeof owsexperiencingturbulentboundarylayersep arationareoutofreachofwhole-domainLESsin cetheboundarylayerneedstoberesolved,rath erthanmodelledifthenear-wall owsand,consequently,DESo owoverasectionofacircularcylinderatasupe r-critical(tur-bulentboundarylayersepara tion) (S-A) ,three-dimensionalstructuresquickly owoveracircularcylinderatRe=800; {1021 RoundedSquareOneofthemostsigni cantfactorsa ectingspincharacteristicsformodern ghtersistheforebody,withitscomplexvortic al \building-block" owconsideredaspartoftheChallengeprojecti sthataroundacanon-icalforebodycrosssecti on, [11]haveshownthatthehighReynoldsnumberDE Spredictionsofthe owoverarounded-cornersquareatRe=800; owovera70 deltawinghasbeencomputedataReynoldsnumbe rof1:56 106[14].}

6 Inthisef-fort,akey ndingwasthattheRANS model(S-A)wasabletoaccuratelypredictthes econdarysepara-tion, ,withDESgivingamorerealisticpre-dictiono fthe ,infact, [15]waspredictedusingDESandcomparedtoLES andRANS results[16].Thee ,showingsig-ni owover70 ,andthe ,ontheotherhand,wasunabletoadequatelyres olvetheboundarylayer, ,thepitchupof2-DNACA0012air-foilwascompu tedforthesameconditionsasreportedbyMorga nandVisbal[17].ThecalculationwasataReyno lds12,600, [17], {1021 MorganandVisbal[17].Anglesoftheprimary,s ec-ondary,andtertiaryvortexformationalso agreedwellwiththepreviouscomputationsand theexperimentsofGendrich[18]. { ,thestructureoftheseparated owatx=L=0 ,thetriptermssummarizedaboveintheS-Amode lareneededandactivatedatx=L=0:2toproduce thee , ,theforebodyshowninFigure7isthree-dimens ional, owistheexistenceofrotarybal-ancedatafort hegeometrythatexistsforanglesofattackof6 0and90 .ShowninFigure7isasnapshotoftheinstantan eous owat90 owvisualizationisfromacomputationataReyn oldsnumberbasedonthebodywidthofover2 106, , owat20 owoverathree-dimensionalforebodyat90 ectivelydesigntrucksthatwouldbemoreenerg ye cient, ,etal.}}

7 [19]performedacomprehen-sivewindtunnelte stonanotionaltractor-trailerto5of9 AmericanInstituteofAeronauticsandAstrona uticsPaper2002{1021provideareliabletestc asefordevelopingnumericaltoolsforthepred ictionofthe owsaroundtractor-trailercon ,matchingwindtunneltestsconditions, sideslip, , owoveranotionaltractor-trailer{isosurfac eofvorticitycoloredbypressureC-130 Paratrooperswhosechutesfailtodeploywhens taticlinejumpingoutofthecargobayrampofth eC-130getcaughtinthehighlyenergeticsepar ated , [20]. , thealternatingsidesofthecargodoor, ightReynoldsnumberstoexaminewhate ectReynoldsnumberhasonthe rstDEScalculationoveranaircraftwasmadeby Squiresetal.[21]ontheF-16at45 :1 {vectorscoloredbyupwardcomponentofveloci tycraft, , ,DESpredictedahighlyen-ergeticturbulent ,thedeltawingstudiesofMor-tonetal.[14] , (byLESstandards) (madedi-mensionlessusingthechordandfrees treamvelocity). owovertheF-16at45 angle-of-attack{ ,contoursareofvorticity,andgray { owovertheF-16at45 angle-of-attack{surfacecoloredbypressure , { nescalestructurescapturedbyDESinthis owovertheF/A-18E{surfacecoloredbypressur e, ight-testspinprogram, angle-of-attackhavebeenperformedbyForsyt heetal.}}}}}}}}

8 [22]. :5 106,5:9 106,and10:0 ,requiringaboutfourdaysonthe nestgridtoobtainsu cientsamplestorepresentthetime-averaged ow ,withDESdemon-stratinganabilitytopredict unsteady ectofgridre negridDESresultswerewithin5%ofthe ight-testdata,withrelativelylittlesensit ivitytogridre owovertheF-15 Eat65 angle-of-attack{ , {1021 ConcludingRemarksThe rstyearoftheChallengeproject\AnalysisofF ullAircraftwithMassiveSeparationUsingDet ached-EddySimulation"hasprovidedkeyadvan cesinap-plication,assessment, owssuchastwo-andthree-dimensionalforebod iesanddeltawingsestablishedafoundationfo rresolu-tionofseveralissuesimportanttous ingDEStopredictthe ow eldaroundfullaircraft,helpingtoestablish importantguidelinesingridissues,turbulen cetreat-ments, dencelevelwithliftanddragpre-dictionstha tareaccuratecomparedto owsovercomplexcon gura-tionsandat , , , , , ,\StrategiesforTurbulenceModel-ingandSim ulations," ,Corsica,May24-26, , ,JouW-H.,StreletsM.,andAllmaras, ,\CommentsontheFeasibilityofLESforWings, andonaHybridRANS/LESAp-proach,"Advancesi nDNS/LES, ,Aug4-8,1997,GreydenPress, ,M.}}

9 ,Spalart, ,Strelets,M.,andTravin,A,\Detached-EddyS imulationofanAirfoilatHighAngleofAttack, ,Corsica,May24-26, ,M.,\DetachedEddySimulationofMas-sivelyS eparatedFlows",AIAA01-0879, , ,Strang,W.,Ho mann, ,\Val-idationofSeveralReynolds-AveragedT urbulenceModelsina3 DUnstructuredGridCode,"AIAA00-2552, , ,Tomaro, ,Grismer, ,\TheDe ningMethodsofCobalt60:aParallel,Implicit ,UnstructuredEuler/Navier-StokesFlowSolv er,"AIAA99-0786, , ,Strang, ,andSankar, ,\AnImplicitAlgorithmforSolvingTimeDepen -dentFlowsonUnstructuredGrids,"AIAA97-03 33, , ,Strang, ,Tomaro, , ,\ Cobalt :AParallel,Im-plicit,Unstructure dEuler/Navier-StokesSolver,"AdvancesinEn gineeringSoftware, , , |373, ,G.,andKumar,V., ,De-partmentofComputerScience,Minneapoli s,MN55455, ,G.,Schloegel,K.,andKumar,V, ,DepartmentofComputerSci-ence,Minneapoli s,MN55455, , ,Forsythe, , ,\Detached-EddySimulationoftheseparated owaroundaforebodycross-section",Directan dLarge-EddySimulationIV,ERCOFTACS eries{Volume8, , ,editors,KluwerAcademicPress, , , , ,1994,\AOne-EquationTurbulenceModelforAe rodynamicFlows,"LaRechercheAerospatiale1 , , ,\ImprovedTwo-Equationk-!}

10 Tur-bulenceModelsforAerodynamicFlows,"NA SA-TM-103975, , ,Forsythe, ,Mitchell, ,Hajek,D.,\DESandRANSS imulationsofDeltaWingVorticalFlows",AIAA 02-0587, {102115 Herrin, ,Dutton, ,\SupersonicBaseFlowExperimentsintheNear WakeofaCylindricalAf-terbody,"AIAAJ ournal, ,No1, , ,Ho mann, ,Squires, ,\Detached-EddySimulationwithCompressibi lityCorrectionsAppliedtoaSupersonicAxisy mmetricBaseFlow",AIAA02{586, , ,Visbal, ,\SimulationofUn-steadyThree-dimensional SeparationonaPitchingWing",AIAA01-2719, ,C.,DynamicStallofRapidlyPitchingAirfoil s:MTVexperimentsandNavier-StokesSim-ulat ion, ,MichiganStateUniversity, , ,Ross, ,Heineck, ,Walker, ,Driver, ,Zilliac, ,\AnExperi-mentalStudyoftheGroundTranspo rtationSystem(GTS)ModelintheNASAAmes7-by 10-FtWindTunnel," ,W.,Trickey,C.,Forsythe,J.,Albertson,J., Leigh,E.,\ExperimentalandComputationalIn vestigationoftheFlowBehindaC-130withTail -gateDown,"AIAA02-0713, , ,Forsythe, ,Wurtzler, ,Strang, ,Tomaro, ,Grismer, ,andSpalart, ,\TowardsPredictionofAircraftSpin,"HighP erformanceComputingUsersGroupMeeting,200 1, , ,Squires, ,Wurtzler, ,Spalart, ,\Detached-EddySimulationofFighterAircra ftatHighAlpha,"AIAA02-0591, {1021}}}