简介：Nonlinearinteractionsofthetwo-dimensional(2D)secondmodewithobliquemodesarestudiednumericallyinaMach6.0flat-plateboundarylayer,focusingonitsselectiveenhancementeffectonamplificationofdifferentobliquewaves.Evolutionofobliquemodeswithvariousfrequenciesandspanwisewavenumbersinthepresenceof2Dsecondmodeissimulatedsuccessively,usingamodifiedparabolizedstabilityequation(PSE)method,whichisabletosimulateinteractionoftwomodeswithdifferentfrequenciesefficiently.Numericalresultsshowthatobliquemodesinabroadbandoffrequenciesandspanwisewavenumberscanbeenhancedbythefiniteamplitude2Dsecondmodeinstabilitywave.Theenhancementeffectisaccomplishedbyinteractionofthe2Dsecondmode,theobliquemode,andaforcedmodewithdifferencefrequency.Twotypesofobliquemodesarefoundtobemoreamplified,i.e.,obliquemodeswithfrequencyclosetothatofthe2Dsecondmodeandlow-frequencyfirstmodeobliquewaves.Eachofthemmaycorrespondtoonetypeoftransitionroutesfoundintransitionexperiments.Thespanwisewavenumberoftheobliquewavepreferredbythenonlinearinteractionisalsodeterminedbynumericalsimulations.