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1、Chap4TurbulenceModellingandDiscretisationApproachesInComputationalWindEngineeringChap4TurbulenceModellingandDiscretisationApproachesInComputationalWindEngineering4.1IntroductionInpreviouschapters,theconventionalbuffetingresponseanalysismethodsbasedontheFEMhave
2、beenreviewedandcompared,whicharealsoknownasthesemi-experimentalandstatisticalapproach.Althoughthesemethodshavebeenwidelyused,somesemi-experimentalfunctionssuchasjointacceptanceoraerodynamicadmittanceandquasi-steadyassumptionareappliedintheanalysis.Thereforeeng
3、ineersarestrivingformoreaccuratenumericalmodels.Windtunnelexperimentaltechniquemaybeagoodchoice,butthehighcostandtimeconsumingnatureofitcannotbewidelyaccepted.WiththedevelopmentofCFDtheoryandnumericalmethods,whethertheCFDtechniquecanbeappliedtosimulatebridgest
4、ructurebuffetingresponseisworthwhilestudy,asthistechniqueiscreatedbasedonthepurefluidfield.HoweverduringtheprocessofapplyingtheCFDmethodinsimulatingtheproblemsofcomputationalwindengineering(CWE),themostimportantproblemishowtodiscretisizeandclosetheNavier-Stoke
5、sequation,toobtainsuchaim,inthischapterturbulencemodelssuitableforcatchingwindtimevaryingcharacteristicsinwindengineeringalongsomeproblemsexistingintheCWEwillbediscussedandnumericaldiscretisationmethodssuchasthefinitevolumemethod(FVM),thefiniteelementmethod(FE
6、M),thefinitedifferencemethod(FDM),theboundaryelementmethod(BEM),thediscretevortexmethod(DVM)andtheSpectralMethod(SM),whicharesuitableforsimulatingthebuffetingresponsewillbeintroducedanddiscussed.4.2TurbulenceModellingDevelopmentAsintroducedinchapter1,buffeting
7、responseisinducedbythewindturbulence,whichisacomplexphysicalphenomenon,andassuchithasbeenthefocusofmuchtheoreticalattentionandexperimentalandnumericalanalysesforalongtime.ThestandardinstantaneousNavier-Stokesequationforincompressibleflowcanbeusedtodescribewind
8、fieldmathematically,hereonlytheinstantaneouscontinuityequation(Eq.4.2.1a)andmomentumequation(Eq.4.2.1b)areexpressed:(4.2.1a)(4.2.1b)Where(4.2.2a)(4.2.2b)-89-Chap4TurbulenceModellin
