Time-resolved visualization of coherent structures during supersonic boundary layer transition

The coherent structures arising during flat-plate boundary layer transition at Mach num-ber 3.4 are investigated using a custom-built hyper-rate imaging system. The evolution of transi-tional structures is investigated in the Eulerian and Lagrangian reference frames. The upstream evolution of transition is dominated by the generation of new hairpin structures, while the interac-tion among multiple structural types dominates the evolution downstream. The breakdown of the existing structure, which may be caused by interactions among multiple types of structures with sim-ilar scales, is also visualized.(c) 2023 Production and hosting by Elsevier Ltd. on behalf of Chinese Society of Aeronautics and Astronautics. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).

Automated summary

This study investigates the coherent structures that arise during flat-plate boundary layer transition at Mach number 3.4 using a custom-built hyper-rate imaging system. The evolution of transitional structures is examined in both the Eulerian and Lagrangian reference frames. The upstream evolution is dominated by the generation of new hairpin structures, while the downstream evolution is mainly influenced by interactions among multiple structural types. The breakdown of existing structures, possibly due to interactions among structures with similar scales, is also observed.