The evolution of Görtler vortices and its interaction with other instabilities are investigated in this paper. Both the Mack mode and the Görtler mode exist in hypersonic boundary-layer flows over concave surfaces, and their interactions are crucially important in boundary layer transition. We carry out a direct numerical simulation to explore the interaction between the Görtler and the oblique Mack mode. The results indicate that the interaction between the forced Görtler mode and the oblique Mack mode promotes the onset of the transition. The forced oblique Mack mode is susceptible to nonlinear interaction. Because of the development of the Görtler mode, the forced Mack mode and other harmonic modes are excited.
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