The stationary Görtler instability in hypersonic flow over a concave wall is systematically investigated across a range of geometric and flow parameters using resolvent analysis, which seeks for the forcing and response pair that maximizes the energy amplification. The optimal forcing takes the form of streamwise vortices, while the optimal response is streamwise streaks. The growth of the optimal disturbance is contributed by both the lift-up and centrifugal mechanisms. The latter becomes dominant as the boundary layer develops, and its growth rate agrees well with that predicted by local stability analysis. In terms of changes in geometric parameters, an increase in curvature destabilizes the Görtler instability, as expected, while the effect of the angle subtended by the concave wall (the turning angle) is shown to be negligible. With respect to changes in flow parameters, the Görtler instability is stabilized at low Reynolds numbers, destabilized under the cold-wall effect, and insensitive to the change in Mach number. The most amplified spanwise wavelength scales with the boundary-layer thickness, which remains mostly unchanged when the freestream Mach number is varied from 3 to 10. A new dimensionless wavelength parameter is proposed to predict the wavelength of the most dangerous Görtler vortices in the compressible flow regime. The resolvent analysis results are confirmed by a three-dimensional numerical simulation, where the hypersonic flow is perturbed by a spatial white noise.
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June 2023
Research Article|
June 14 2023
Global and local analyses of the Görtler instability in hypersonic flow
Special Collection:
Hypersonic Flow
Uy Ken Chun Kit (黃駿傑)
;
Uy Ken Chun Kit (黃駿傑)
(Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Validation, Writing – original draft, Writing – review & editing)
Department of Aeronautical and Aviation Engineering, The Hong Kong Polytechnic University
, Hung Hom, Kowloon, Hong Kong
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Hao Jiaao (郝佳傲)
;
Hao Jiaao (郝佳傲)
a)
(Conceptualization, Data curation, Investigation, Methodology, Project administration, Resources, Software, Supervision, Writing – review & editing)
Department of Aeronautical and Aviation Engineering, The Hong Kong Polytechnic University
, Hung Hom, Kowloon, Hong Kong
a)Author to whom correspondence should be addressed: jiaao.hao@polyu.edu.hk
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Wen Chih-Yung (温志湧)
Wen Chih-Yung (温志湧)
(Conceptualization, Funding acquisition, Project administration, Resources, Supervision, Writing – review & editing)
Department of Aeronautical and Aviation Engineering, The Hong Kong Polytechnic University
, Hung Hom, Kowloon, Hong Kong
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a)Author to whom correspondence should be addressed: jiaao.hao@polyu.edu.hk
Note: This paper is part of the special topic, Hypersonic Flow.
Physics of Fluids 35, 064111 (2023)
Article history
Received:
March 21 2023
Accepted:
May 31 2023
Citation
Ken Chun Kit Uy, Jiaao Hao, Chih-Yung Wen; Global and local analyses of the Görtler instability in hypersonic flow. Physics of Fluids 1 June 2023; 35 (6): 064111. https://doi.org/10.1063/5.0151349
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