Boundary-Layer Transition for a circular cone at Mach 4 (June 2021): AFOSR Social Media AFOSR 60th Monograph AFOSR Broad Agency Announcements Other email Yes, add me to the mailing list. No, do not add me to the mailing list. Yes No Along a flight-trajectory a hypersonic vehicles encounters a wide range of flow conditions. This change in flow conditions can drastically alter the dominant nonlinear mechanisms leading to transition in high-speed boundary layers. At ”lower” Mach numbers (here Mach 4) a very powerful nonlinear breakdown mechanism, the so-called oblique breakdown, can lead to transition to turbulence over a very short downstream distance. The artwork above was inspired to visualize this very rapid breakdown mechanisms. The structures shown above show temperature disturbances and confirm that the boundary-layer becomes turbulent over just a few disturbance wavelengths. Understanding how Mach number impacts the transition behavior, and therefore the associated skin-friction and heat transfer increase is required to design and safely operate next generation high-speed/hypersonic vehicles. Contributors: Christoph Hader, Hermann F. Fasel