Oblique breakdown for a blunt cone at Mach 6 (May 2019): The effect of nose bluntness on high-speed boundary-layer remains a topic of great interest. While it is known that nose bluntness stabilizes the boundary layer it has been observed in wind tunnel experiments in so-called “conventional” or noisy facilities that transition suddenly moves upstream with increasing nose bluntness (transition reversal). Although this phenomenon was observed over 3 decades ago it is still not fully understood what causes transition reversal. Although nose bluntness has a stabilizing effect it also gives rise to a new instability, the so-called entropy layer instabilities. The artwork above shows how transition can be initiated on a blunt cone just downstream of the nose by forcing a pair of oblique waves in the entropy layer. The contours on top show how the disturbance waves propagate along the entropy layer and grow in amplitude until they contaminate the boundary layer and subsequently lead to rapid laminar-turbulent boundary layer transition. The isosurfaces of the Q-vortex identification criterion display the various breakdown stages of a high-speed boundary layer all the way to turbulence. Contributors: Andrew Hartman, Christoph Hader, Hermann F. Fasel