湍流局部結(jié)構(gòu)分析和渦旋識(shí)別.pdf

1、南昌大學(xué)碩士學(xué)位論文湍流局部結(jié)構(gòu)分析和渦旋識(shí)別姓名：趙勇申請(qǐng)學(xué)位級(jí)別：碩士專業(yè)：工程力學(xué)指導(dǎo)教師：鄒文楠李相麟20060501LocalstructureanalysisinturbulenceandvortexdetectionABSTRACTThestatisticalanalysisofturbulentfluctuationsignalscallbedividedintotwocategories，largeamountsamp

2、leanalysisandlocaltime—frequencyanalysisrespectivelyWiththetoolofwaveletanalysis，theauthordidsometimefrequencyanalysesonthebasementofanexperimentalflowinteractedbetweenboundary—layerandwakeTheconclusionsareasfollows，thev

3、ortexesformedbythewake’Sfallingoffmechanismaremorethanthosebytheboundary—layerinquantity，s仃ongerinpowerandcompacterinstructure；theplaceofthewake’Sstrongestshearproducewellvortexesbothinquantityandquality，butbuststructure

4、sCanbefoundintheboundarylayeroccasionally；vortexesintheinverseenergycascaderegionareweakandincompactduetolackofvortexformingmechanism，andthelinearscalingdoesnotexistatsmallspatialscalebecauseofstrongfluctuationinthesmall

5、scaleMeanwhile，theflowapproachtolocallyisotropicanduniformturbulenceiftheflowconditionissimple，andvortexesherearecompacterthanotherplace，viceversaThewavelettheoryisintroducedinbriefthenseveralapplicationsinturbulencearer

6、eferredincludinghowstrongintermittencymakesthescalingexponentofvelocitystructuredeviates，fromtheK41theory’slinearscalinglawwhenordernumberisrelativelylargeThecoherentstructureisdefined，weconsiderit’Salargestructurewithac

7、ertainpowerfulfluctuation；thenanewmethodforcoherentstructuredetectionisputforward，ietheminimumofenergymtiocriterion，whichismoreobjectiveandmeaningfulthanthepreviousmethodsThelastchapterintroducesanewmethodofvortexdetecti

8、on，whichisbasedonthestreamlineandstreamline—cluster’Stopologicalcharacteristics，thenseveralexamplesareusedtoverifytheeffectivenessofthismethodGraduate：Zhaoyong(engineeringmechanics)Directedby：ViceprofessorZouwennailKeywo