Thenatureofthethree-dimensionaltransitionarisingintheflowpastacylinderisinvestigatedbyapplyingtheLifschitz-HameiritheoryalongspecialLagrangiantrajectoriesexistinginitswake.ResultsshowthatthevonKarmanstreetisunstablewithregardtoshort-wavelengthperturbations.Theasymptoticanalysispredictsthepossibleexistenceofbothsynchronous(asmodesAandB)andasynchronous(asmodeC)instabilities,eachassociatedtospecificLagrangianorbits.Theproposedstudyprovidesusefulqualitativeinformationontheoriginofthedifferentmodesbutnoquantitativeagreementbetweenthegrowthratespredictedbytheasymptoticanalysisandbyaglobalstabilityanalysisisobserved.Thereasonsforsuchmismatcharebrieflydiscussedandpossibleimprovementstothepresentanalysisaresuggested.
