Convective instabilities in a laminar shock-wave/boundary-layer interaction

Niessen, Sébastien; Groot, Koen J.; Hickel, Stefan; Terrapon, Vincent

doi:10.1063/5.0135590

Cited by 3 publications

(1 citation statement)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, research on cross-flow over a forward-facing step identified novel mechanisms that impact the instability growth rates on a local scale (Eppink 2020;Rius-Vidales & Kotsonis 2021). In shock-boundary-layer interactions (SBLIs), Niessen et al (2023) used an energy analysis to show how the large streamwise gradients resulting from the SBLI can result in significant stabilizing or destabilizing effects, depending on the disturbance location relative to the SBLI. These studies illustrate how in-depth analysis of physical mechanisms provide important insight when studying instabilities in complex flows.…”

Section: Introductionmentioning

confidence: 99%

Boundary-layer instability on a highly swept fin on a cone at Mach 6

Peck,

Groot,

Reed

2024

J. Fluid Mech.

Self Cite

View full text Add to dashboard Cite

The growth and characteristics of linear, oblique instabilities on a highly swept fin on a straight cone in Mach 6 flow are examined. Large streamwise pressure gradients cause doubly inflected cross-flow profiles and reversed flow near the wall, which necessitates using the harmonic linearized Navier–Stokes equations. The cross-flow instability is responsible for the most-amplified disturbances, however, not all disturbances show typical cross-flow characteristics. Distinct differences in perturbation structure are shown between small ( $\sim$ 3–5 mm) and large ( $\sim$ 10 mm) wavelength disturbances at the unit Reynolds number $Re' = 11 \times 10^6$ m $^{-1}$ . As a result, amplification measurements based solely on wall quantities bias a most-amplified disturbance assessment towards larger wavelengths and lower frequencies than would otherwise be determined by an off-wall total-energy approach. A spatial-amplification energy-budget analysis demonstrates (i) that wall-normal Reynolds-flux terms dictate the local growth rate, despite other terms having a locally larger magnitude and (ii) that the Reynolds-stress terms are responsible for large-wavelength disturbances propagating closer to the wall compared with small-wavelength disturbances. Additionally, the effect of free-stream unit Reynolds number and small yaw angles on the perturbation amplification and energy budget is considered. At a higher Reynolds number ( $Re' = 22 \times 10^6$ m $^{-1}$ ), the most-amplified wavelength shrinks. Perturbations do not behave self-similarly in the thinner boundary layer, and the shift in most-amplified wavelength is due to decreased dissipation relative to the lower-Reynolds-number case. Small yaw angles produce a streamwise shift in the boundary layer and disturbance amplification. The yaw results quantify a potential uncertainty source in experiments and flight.

show abstract

Section: Introductionmentioning

confidence: 99%

Boundary-layer instability on a highly swept fin on a cone at Mach 6

Peck,

Groot,

Reed

2024

J. Fluid Mech.

Self Cite

View full text Add to dashboard Cite

show abstract

Global instability of the interaction between an oblique shock and a laminar boundary layer

Song,

Hao

2023

Physics of Fluids

View full text Add to dashboard Cite

This study investigates the oblique shock-wave/boundary-layer interaction with a Mach number of 2.15 and a Reynolds number of 1×105. Both global stability analysis and direct numerical simulation are used to reveal the global instability characteristics and three-dimensional details of the incident shock flow. The results of global stability analysis indicate that stationary global instability occurs when the shock angle exceeds the critical angle 31.8°. At a shock angle equal to 33°, an additional unstable mode appears, which is oscillatory at large wavelength and gradually dominant when the wavelength decreases. As the wavelength is further reduced, the mode and its conjugation evolve into two stationary modes with different growth rates. A global instability criterion for incident shock flow is established based on the triple deck theory, which determines the instability only through free-stream conditions and shock angles. A direct numerical simulation is performed for the 32° shock angle case. It is found that secondary separation occurs during the nonlinear growth, which is absent in the two-dimensional base flow. Moreover, the separated flow undergoes a secondary perturbation growth, during which the dominant spanwise wavelength is doubled and the flow structures change significantly. The flow oscillates around a quasi-steady state in the end, indicating that a stationary unstable mode can develop unsteadiness without external disturbances.

show abstract

Investigation of streamwise streak characteristics over a compression ramp at Mach 4

Zhao,

Ma,

Chen

et al. 2024

Physics of Fluids

View full text Add to dashboard Cite

Experiments of shock wave/boundary layer interactions over a nominally two-dimensional compression ramp are conducted in a Mach 4 Ludwieg tube tunnel. Measurements of Schlieren, Rayleigh scattering, and surface pressure are performed to present the relevant flow features. The effects of two parameters, namely the Reynolds number based on the length of the flat plate and the ramp angle, on the flow stabilities are focused on. Four ramp angles of 6°, 8°, 10°, and 12° are tested under a Reynolds number of 7.22 × 105, while two other Reynolds numbers (3.66 × 105 and 9.19 × 105) are investigated with a ramp angle of 10°. Streamwise streaks are observed downstream of the reattachment point. The spanwise wavelength of the streaks remains unchanged with different ramp angles, whereas it slightly decreases as the Reynolds number increases. Power spectral density results show that the flow is transitional in the streak region and becomes turbulent where streaks break down. When increasing the ramp angle or the Reynolds number, the streamwise length of streaks shrinks. Two different patterns are distinguished at the breakdown, resembling the two unstable modes observed in the breakdown of Görtler vortices. To clarify the underlying physics of the formation of streaks, global stability analysis and resolvent analysis are carried out. Two regions of maximum optimal gain are identified, which are associated with Mack's first mode and streaks. The former can serve as an initial seed of Görtler instability via nonlinear interaction, while the latter can be associated with transient growth due to the lift-up mechanism and Görtler instability.

show abstract

Convective instabilities in a laminar shock-wave/boundary-layer interaction

Cited by 3 publications

References 59 publications

Boundary-layer instability on a highly swept fin on a cone at Mach 6

Boundary-layer instability on a highly swept fin on a cone at Mach 6

Global instability of the interaction between an oblique shock and a laminar boundary layer

Investigation of streamwise streak characteristics over a compression ramp at Mach 4

Contact Info

Product

Resources

About