低Re數(shù)下橫向排列雙圓柱繞流的POD數(shù)值模擬和整體穩(wěn)定性分析.pdf

1、囤論文題目低Re數(shù)下橫向排列雙圓柱繞流的作者姓名學科專業(yè)導師姓名完成時間POD數(shù)值模擬和整體穩(wěn)定性分析孫德軍教援二o0^年六月AbstractABSTRACTFlowproperties，flowpaaemformation，criticalReynoldsnumber，flowbifurcation，andetc，areexploredinaspectsofdirectnumericalsimulationandglobalinsta

2、bilityanalysisbasedonPODGalerkinlowdimensionalmodelrespectivelyinthisthesis。Themainworkinclude：(1)Thefluidfieldofflowpasttwoside—bysidecircularcylindersatdifferentparametersisnumericallysimulatedbylowdimensionalPODGalerk

3、inmodelIt’ScomparedwithreconstructedfluidfieldbyPODbasisfunctionandtheonebyFLUENTsimulationThedifferentflowpatternsatdifferentparametersweconfirmedviastudyoftheflowfieldproperties(2)Aglobalstabilityanalysisfortheissueisa

4、lsoperformedbyChibamethodonthebasisofthelow—dimensionmodelBytheflow—fieldreconstructionwiththedominanteigenfunction，itisfurtherprovedthatdifferentbifurcationpathsunderflowswithdifferentparametersareinducedbythethecorresp

5、ondingunstablemode。(萄Atsmallgapratio，thereexistsaHopfbifurcationwhenflowswitchsfromsinglebluffbodysteadypatterntosinglebluffbodyperiodicpaRern(b)AtthemoderategapratioT／D=15，withfirstoneHopfbifurcaion，thenonepitchforkbifu

6、rcation，thecorrespodingflowpatternswitchsfirstfromsymmetricsteadyflowtooscillatoryflowthenfromoscillatoryflowtodeflectedoscillatoryflow；AtgapratioT／D=16，withpitchforkbifurcationfirst，thenHopfbifurcation，thecorrespondingf

7、lowpaRernswitchsfirstfromsteadysymmetricflowtosteadyasymmetricflowthenfromsteadyasymmetricflowtodeflectedoscillatoryflowWithtwodifferentgapratios，thedifferentbifurcationsequencesareinducedbythefardownstreammodewhichcontr

8、olsthevortexsheddingandthestationarymoderelatedtothedeflectionWhenthemoderategapratioT／Dissetto15，themostdominantfardownstreammodemakestheHopfbifurcationhappenfirst；WhenthemoderategapratioT／Dissetto16，themostdominantstat

9、ionarymodemakesthepitchforkbifurcationhappenfirst(c)Atbiggapratio，thereexistsaHopfbifurcationwhenflowswitchsfromseparateddoublebodysteadypatterntoantiphasesynchronizedpatternorinphase—synchronizedpatternTheflowpatternsaf