Input-Output Analysis of Shock Boundary Layer Interaction

Sidharth, G. S.; Candler, Graham V.; Nichols, Joseph W.; Jovanović, Mihailo R.

doi:10.2514/6.2018-3220

Cited by 20 publications

(5 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For a given temporal frequency , we use a matrix-free approach (Dwivedi et al. 2018) to compute the largest singular value of . Note that, at any , denotes the largest induced gain with respect to Chu’s compressible energy norm (Hanifi, Schmid & Henningson 1996), where ( ) identify the spatial structure of the dominant I/O pair.…”

Section: Input–output Formulation For Compressible Flowsmentioning

confidence: 99%

“…The columns d i of the matrix D represent the input forcing directions that are mapped through the frequency response H to the corresponding columns φ i of the matrix Φ; for d = d i , the output φ is in the direction φ i and the amplification is determined by the corresponding singular value σ i . For a given temporal frequency ω, we use a matrix-free approach (Dwivedi et al 2018) to compute the largest singular value σ 1 (ω) of H(iω). Note that, at any ω,…”

Section: Input-output Formulation For Compressible Flowsmentioning

confidence: 99%

“…Furthermore, this location is sufficiently upstream of the neutral point of the acoustic instability, which takes place at Re = 1140. This ensures that any non-modal growth arising from the Orr-mechanism (Dwivedi et al 2018) decays before the spatial growth rate of the local acoustic instability becomes positive. Sponge regions are used at the top and right boundaries to model non-reflecting radiation boundary conditions.…”

Section: Two-dimensional Unsteady Perturbations: Acoustic Amplificationmentioning

confidence: 99%

See 2 more Smart Citations

Reattachment streaks in hypersonic compression ramp flow: an input–output analysis

Dwivedi¹,

Sidharth

Nichols³

et al. 2019

J. Fluid Mech.

Self Cite

View full text Add to dashboard Cite

We employ global input-output analysis to quantify amplification of exogenous disturbances in compressible boundary layer flows. Using the spatial structure of the dominant response to time-periodic inputs, we explain the origin of steady reattachment streaks in a hypersonic flow over a compression ramp. Our analysis of the laminar shock/boundary layer interaction reveals that the streaks arise from a preferential amplification of upstream counter-rotating vortical perturbations with a specific spanwise wavelength. These streaks are associated with heat flux striations at the wall near flow reattachment and they can trigger transition to turbulence. The streak wavelength predicted by our analysis compares favorably with observations from two different hypersonic compression ramp experiments. Furthermore, our analysis of inviscid transport equations demonstrates that base flow deceleration contributes to the amplification of streamwise velocity and that the baroclinic effects are responsible for the production of streamwise vorticity. Finally, the appearance of the temperature streaks near reattachment is triggered by the growth of streamwise velocity and streamwise vorticity perturbations as well as by the amplification of upstream temperature perturbations by the reattachment shock.

show abstract

Section: Input–output Formulation For Compressible Flowsmentioning

confidence: 99%

Section: Input-output Formulation For Compressible Flowsmentioning

confidence: 99%

Section: Two-dimensional Unsteady Perturbations: Acoustic Amplificationmentioning

confidence: 99%

See 1 more Smart Citation

Reattachment streaks in hypersonic compression ramp flow: an input–output analysis

Dwivedi¹,

Sidharth

Nichols³

et al. 2019

J. Fluid Mech.

Self Cite

View full text Add to dashboard Cite

show abstract

“…SBLI separation-induced instability and transition have therefore been the focus of numerous recent hypersonic studies. In particular, significant effort has been made to understand the streamwise streaks visible around reattachment in SBLI flows (Heffner et al 1993;Benay et al 2006;Dwivedi et al 2018;Leinemann et al 2019;Li et al 2022;Wagner 2022;Cao et al 2022), first noted by Ginoux (1965), as well as the role of the bubble in transition location (Dwivedi et al 2018;Vandomme et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Instability and transition onset downstream of a laminar separation bubble at Mach 6

et al. 2023

View full text Add to dashboard Cite

Instability measurements of an axisymmetric, laminar separation bubble were made over a sharp cone-cylinder-flare with a $12^{\circ }$ flare angle under hypersonic quiet flow. Two distinct instabilities were identified: Mack's second mode (which peaked between 190 and 290 kHz) and the shear-layer instability in the same frequency band as Mack's first mode (observed between 50 and 150 kHz). Both instabilities were measured with surface pressure sensors and were captured with high-speed schlieren. Linear stability analysis results agreed well with these measured instabilities in terms of both peak frequencies and amplification rates. Lower-frequency fluctuations were also noted in the schlieren data. Bicoherence analysis revealed nonlinear phase-locking between the shear-layer and second-mode instabilities. For the first time in axisymmetric, low-disturbance flow, naturally generated intermittent turbulent spots were observed in the reattached boundary layer. These spots appeared to evolve from shear-layer-instability wave packets convecting downstream. This work presents novel experimental evidence of the hypersonic shear-layer instability contributing directly to transition onset for an axisymmetric model.

show abstract

“…For example, under the correct scaling of the wall-parallel wavenumbers, the self-similar hierarchies of response modes give rise to self-similar families of vortical structures. However, there has been less work applying this operator based decomposition to fully-developed compressible flows, with the exception of the recent studies on compressible jet flows (Jeun et al 2016;Towne et al 2018;Schmidt et al 2018), subsonic aerofoils (Yeh & Taira 2019), turbulent Couette flows (Dawson & McKeon 2019), and hypersonic boundary layer transitions (Cook et al 2018;Dwivedi et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Resolvent-based study of compressibility effects on supersonic turbulent boundary layers

2019

View full text Add to dashboard Cite

The resolvent formulation of McKeon & Sharma (2010) is extended to the compressible Navier-Stokes equations. Resolvent analysis is applied to the supersonic turbulent boundary layer in order to study the validity of Morkovin's hypothesis, which postulates that high-speed turbulence structure in zero pressure-gradient turbulent boundary layers remains largely the same as its incompressible counterpart. Supersonic turbulent boundary layers with adiabatic wall boundary conditions at Mach numbers ranging from 2 to 4 are considered. Resolvent analysis highlights two distinct regions of the supersonic turbulent boundary layer in the wave parameter space: the relatively supersonic region and the relatively subsonic region. In the relatively supersonic region, where the flow is supersonic relative to the freestream, resolvent modes display structures consistent with Mach wave radiation that are absent in the incompressible regime. In the relatively subsonic region, we show that the low-rank approximation of the resolvent operator is an effective approximation of the full system and that the response modes predicted by the model exhibit universal and geometrically self-similar behaviour via a transformation given by the semi-local scaling. Moreover, with semi-local scaling, we show that the resolvent modes follow the same scaling law as their incompressible counterparts in this region, which has implications for modelling and the prediction of turbulent high-speed wall-bounded flows. We also show that the thermodynamic variables exhibit similar mode shapes to the streamwise velocity modes, supporting the strong Reynolds analogy. Finally, we demonstrate that the principal resolvent modes can be used to capture the energy distribution between momentum and thermodynamic fluctuations.

show abstract

Input-Output Analysis of Shock Boundary Layer Interaction

Cited by 20 publications

References 38 publications

Reattachment streaks in hypersonic compression ramp flow: an input–output analysis

Reattachment streaks in hypersonic compression ramp flow: an input–output analysis

Instability and transition onset downstream of a laminar separation bubble at Mach 6

Resolvent-based study of compressibility effects on supersonic turbulent boundary layers

Contact Info

Product

Resources

About