Instability of streaky high-supersonic boundary layers over cooled walls
Abstract
We investigate the instability of streaks induced by free-stream vortical disturbances in cooled-wall high-supersonic boundary layers. Distinct types of instability modes are identified: modified Mack second modes, a newly discovered varicose secondary-instability mode and sinuous or varicose secondary-instability modes akin to those in incompressible boundary layers. Unique characteristics of the new secondary-instability mode are that its eigenfunctions concentrate in high-speed valley regions near the wall and feature intense temperature fluctuations at the wall. The streaks in high-supersonic boundary layers destabilise the three-dimensional secondary-instability modes, but suppress the growth of the modified Mack second modes, both radiating and non-radiating. The suppression of radiating modes amounts to a reduction of the two-dimensional noise they emit. Numerical results indicate that, unlike streaks in adiabatic-wall boundary layers, whose instability concentrates in low-speed peak regions away from the wall, the secondary instability of streaks in cooled-wall high-supersonic boundary layers occurs both in low-speed peak regions and in high-speed valley regions.
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BibTeX
@misc{xu2026instability,
title = {{Instability of streaky high-supersonic boundary layers over cooled walls}},
author = {Dongdong Xu and Pierre Ricco and Elena Marensi and Xuesong Wu},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.00846},
eprint = {2611.00846},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.00846},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Instability of streaky high-supersonic boundary layers over cooled walls
AU - Dongdong Xu
AU - Pierre Ricco
AU - Elena Marensi
AU - Xuesong Wu
PY - 2026
DA - 2026/11/01
PB - arXiv
DO - 10.48550/arxiv.2611.00846
UR - https://arxiv.org/abs/2611.00846
AB - We investigate the instability of streaks induced by free-stream vortical disturbances in cooled-wall high-supersonic boundary layers. Distinct types of instability modes are identified: modified Mack second modes, a newly discovered varicose secondary-instability mode and sinuous or varicose secondary-instability modes akin to those in incompressible boundary layers. Unique characteristics of the new secondary-instability mode are that its eigenfunctions concentrate in high-speed valley regions near the wall and feature intense temperature fluctuations at the wall. The streaks in high-supersonic boundary layers destabilise the three-dimensional secondary-instability modes, but suppress the growth of the modified Mack second modes, both radiating and non-radiating. The suppression of radiating modes amounts to a reduction of the two-dimensional noise they emit. Numerical results indicate that, unlike streaks in adiabatic-wall boundary layers, whose instability concentrates in low-speed peak regions away from the wall, the secondary instability of streaks in cooled-wall high-supersonic boundary layers occurs both in low-speed peak regions and in high-speed valley regions.
ER -