schlieren photography on freely flying hawkmoth yun liu文献.pdf

该【schlieren photography on freely flying hawkmoth yun liu文献 】是由【小舍儿】上传分享，文档一共【4】页，该文档可以免费在线阅读，需要了解更多关于【schlieren photography on freely flying hawkmoth yun liu文献 】的内容，可以使用淘豆网的站内搜索功能，选择自己适合的文档，以下文字是截取该文章内的部分文字，如需要获得完整电子版，请下载此文档到您的设备，方便您编辑和打印。Downloadedfromhttp://rsbl./onMay18,,JesseRoll2,StephenVanKooten2andXinyanDeng21DepartmentofMechanicalandCivilEngineering,PurdueUniversityNorthwest,Westville,IN46391,USAResearch2SchoolofMechanicalEngineering,PurdueUniversity,585PurdueMall,WestLafayette,IN47906,USAXD,0000-0001-8694-7833Citethisarticle:LiuY,RollJ,VanKootenS,-:://dx./.plexitiesandtheinherentdifficultiesinstudyingflyinginsectsinanatu-ralsetting,,Schlieren,awidelyusedtechniqueforhigh-speedflowvisualization,wasadaptedtocapturethevortexstructuresReceived:21March2018aroundfreelyflyinghawkmoth(Manduca).Flowfeaturessuchasleading-Accepted:20April2018edgevortex,trailing-edgevortex,-basedopticalflowmethod,:bioengineering,biomechanicsKeywords:,flowvisualization,plexflowtopologyofflappingwings,revealedthroughsmokevisual-vortexstructure,Schlierenizationconductedoninsectsandroboticflappers,establishedtheprominenceofastablyattachedleadingedgevortex(LEV)responsibleforliftaugmentationininsectflight[1,2].Furthercharacterizedbyscaledtankexperimentswithroboticflappers,quantitativeforcedatawerecorrelatedtomodelsoftheAuthorforcorrespondence:quasi-steadyaerodynamicmechanismsformulatedfromdetailedoiltankXinyanDengexperiments[3].Inthelightofflowquantificationtechniques,-mail:******@imagevelocimetry(PIV),thestudyofflappingwingaerodynamicsprogressedtoenableaquantitativedepictionandmeasurementsofflowstructuresgener-atedbyflyinganimals[4–6].Theseflowinvestigationstypicallyconsistedoflocalizedtwo-dimensionalflowmeasurements,providingsignificantinsightintothenatureofanimalflight,buttheywerelimitedintheirdepictionofthree-,withtheadvancementsintomographic-PIV,essfullycapturedandreconstructedthree-dimensionallyonatetheredlocust[7].None-theless,onlyflowinthefar-field,awayfromthetetheredlocust,,ontheotherhand,havebeenusedtovisualizethree-dimensionalflowinflyinganimals[8–10].Smokeplumevisualizationonahoveringhum-mingbirdwasusedtoreconstructthenear-fieldthree-dimensionalflowstructureinthedownwash[8].Yet,thesevisualizationmethodsonlydepictpat-ternsofstreak-linesintheunsteadyflow,leavingthevortexstructurestobeplexsmokepatterns[11].HereweapplySchlierenphotography,awidelyusedflowvisualizationmethodinhighspeedflow[12],onfreelyflyinghawkmoth(Manducasexta),usingalcoholvapourasapassivescalar[11]tocaptureandvisualizethethree--basedopticalflowmethod[13]isthenusedtoquantifythenear-onlineathttps://dx./,.&2018TheAuthor(s)://rsbl./onMay18,2018(a)(b)(c)(d)2fore---wingtipvortexrootvortexrootvortexhind-wingtipvortexstarting/vortexloopsstoppingvortex(e)(f)(g)(h)--wingtipvortex1420180198:fore-wingrootvorticesrootvortexhind-wingtipvortexvortexloopvortexlooptipvortexhind-wingtipvortexvortexloopscreatedindown--hoveringmalehawkmoth().(a)Acombinedstructureofstarting/stoppingvortexafterwingpronation.(b)Tipvorticescreatedfromtipsofforeandhind-wings.(c)Anattachedcone-shapedleadingedgevortexbeforewingsupination.(d)Anillustrativedepictionofthevortexstructurecreatedinthedown-stroke.(e)Thevortexloopcreatedinthedown-strokeshedsintothewake.(f–g)Long,stretchedtipvorticesgeneratedfromthetipsoffore-andhind-wingsandconnectedtotheshedvortexloops.(h)Anillustrativedepictionofthevortexstructurecreatedintheup---(measuredsystemwasimplementedtovisualizetheunsteadythree-’smotionover300imageframes).consistsoftwosinglemirror,double-pass,Schlierenset-upswithFigure1a–dshowstheimagesofvortexstructureinthetwohighspeedcameras(MiniUX100,Photron),filmingfromdown--,awhiteLEDpingvortexwasobservedoneachwinginthebeginningoflightwasprojectedthrougha1mmpinholeontoa10-inchdiam-down-strokerightafterwingpronation(figure1a).Thenveryeteropticalsphericalmirror(Edmondoptics).Aportionofthequickly,oneachwing,distincttipvorticesweregeneratedreflectedlightwasthenredirectedtowardsthehighspeedcamerafromboththefore-andhind-wing(figure1b).Meanwhile,ausinga50/50(reflection/transmissionratio,Edmondoptics)stableleading-edgevortexwascreatedwithoneendconnectingbeam-,tothefore--arazorbladewasusedastheknife-edgeproducingtheSchlierenedgevortexextendingacrossthethoraxwaspreviouslyimages(seeelectronicsupplementarymaterial,figureS1).ToreportedbyBomphreyetal.[15]fromexperimentsontetheredtracethevorticalflowproducedbytheflappingManducawings,warmisopropylalcohol(91%isopropylalcoholheatedto388C)Manducainawindtunnel,wefoundnoevidenceofsuchawasbrushedontothesurfaceofbothwingsatthebeginningofstructure;instead,acone-(figure1c),ingflowvelocitydifferencebetweentheoverthewingsurfaceincreasesvaporizationofthealcohol,draw-,anopenvortexlooporingitintothevortexsheet/vorticesandformingthepatternofhorseshoe-shapedvortex[1]iscreatedoneachwing,connect--ingtheleading-edgevortex,tipvortex,starting/stoppingmatedtobeontheorderofone,thusformationsdepictedbythevortexandrootvortex(figure1d).(Videoofthevortexstructureuratelycapturethevorticalflowstructuresindown-strokecanbefoundinthevideofile:;seeintheabsenceofsignificantvortexstretching[11].ThroughourDryadrepository:https:///.)highspeedSchlierenphotographysystem,theunsteadythree-,thirtytestswereconductedandresultsmodels[1,16].,theobservanceofthevortexstructurepre-moth’saveragetranslatingspeedwasmeasuredbytrackingansentedinthisworkthusservesasadirectconfirmationofeyeoftheManducausingaMatlabcodedevelopedbyHedrick[14].,uniquetopreviousexperimentalandnumericalstudiesonManduca,theexistenceofasecondaryhind--stroke,duringandhighspeedSchlierenphotography,theoverallvortexthesupination(figure1c),thecone-shapedleadingedgeDownloadedfromhttp://rsbl./onMay18,2018(a)(b)(c)–+.–:––.(a),.(b)Velocityvectorfieldquantifiedusingphysics-basedopticalflowmethod.(c)(a)matcheswellwiththestrongcounter-,undersignificantdeformationduetotherapidwingphysics--twisting,,theleading-ocityvectorsfieldisprovidedinfigure2b,whereaclearedgevortexisshedintothewakealongwiththeothervorticesdownwardflowismeasuredwithamaximumvelocityofcreatedduringthedown-stroke,,-clockwisevorticityregion,figure1e–,aclosedvortexloopshownintheblue,correlateswiththetipvortex,highlightedwasshedintothewakefromeachwingwhiletwosignificantbythereddashedregion,demonstratingthemethod’sabilitytipvorticeswerecreatedfromthetipsoffore-andhind-(figure1g).Concurrently,arootvortexwascreated,vapourasamedium,,,linkedvorticalflowbeha-theflowstructurecapturedinthedown-stroke,wefoundviourswereobservedthroughconventionalflowvisualizationsnoevidenceofasignificantattachedleading-edgevortexandPIVmeasurementsonbirdsandbats[8,17–19].Usingaduringtheup--PIVsystem,streamwisevorticitywasquantifiedonputationalfluidfreelyflyingblackcaps(SylviaatricapillaL.)inawindtunnelatdynamics(CFD)simulationsonahoveringManducamodeldifferenttimeinstancesandspatiallocations,revealinga[1,16],andisindicativeofalackofvortexloopformationlinkedvorticalflowstructureinthewakeregionofthebirdduringtheup-,pletewing[17].Onaslowlyflyingbat,leadingedgevortex,startingbeatcycle,theresultingvortexstructurecreatedundereachvortex,tipandrootvorticeswerecapturedseparatelyfromwingconsistsofavortexloopinthefarwake,twotipvorticesthestream-wiseandspan-wisePIVmeasurements,suggestingandarootvortexinthenearfield.(Videoofthevortexstruc-aclosedloopvortexsystemcreatedduringthedown-stroketureinup-;see[18].Inourstudy,however,theentirevortexringstructureinDryadrepository:https:///.)thedown-strokewascaptureddirectlywithouttheneedforAsshownabove,,-basedopticalflowmethod,quantifi--basedopticalflowmethod,,appropriatelysuitedasavelocityquantificationtoolforflowquantificationofthistypecanonlybeusedtoquantifySchlierenimages[13],,withlimitednumbersofcam-Figure2presentsanexampleofsuchflowvelocityquantifi-eras,thecurrentphysics-,theoriginalSchlierenimagetoflowquantificationonthetwo-dimensionalimagingplanewithaclearlyidentifiedtipvortexhighlightedbytheredrec-andcannotquantifytheflowinthree-