Nonlinear stability and saturation of crossflow vortices in swept-wing boundary layers

n recent years the development of nonlinear parabolized stability equations (NPSE) has opened new pathways toward understanding transitional boundary-layer flows. This is because the elegant inclusion of nonlinear and nonparallel effects in the NPSE allow accurate stability analyses to be performed without the difficulties and overhead associated with direct numerical simulations (DNS). In this work NPSE codes for compressible boundary layers over swept airfoils are developed. Previous work shows that linear stability theories, including the linear parabolized stability equations (LPSE), are unable to accurately describe the transitional flow field for crossflow dominated boundary layers. The NPSE results presented here clearly establish that the nonlinear saturation of crossflow disturbances is responsible for these discepancies. Experimental and theoretical results for the boundary-layer flow over an NLF(2)-0415 swept wing at...