Receptivity: The Inspiration of Mark Morkovin (Invited)

Reed, Helen L.; Saric, William S.

doi:10.2514/6.2015-2471

Cited by 13 publications

(7 citation statements)

References 94 publications

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“…An optimisation-based, non-modal approach (Schmid 2007) and a multiple-scales approach (Zuccher & Luchini 2014) have also been proposed. The reader is directed to Saric, Reed & Kerschen (2002) and Reed & Saric (2015) for detailed reviews of investigations carried out in the field of receptivity. From now on, we will mainly focus on the specificities of the acoustic receptivity problem in subsonic flow conditions.…”

Section: Introductionmentioning

confidence: 99%

An adjoint compressible linearised Navier–Stokes approach to model generation of Tollmien–Schlichting waves by sound

2019

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The generation of the first-mode instability through scattering of an acoustic wave by localised surface roughness, suction or heating is studied with a time-harmonic compressible adjoint linearised Navier–Stokes (AHLNS) approach for subsonic flow conditions. High Strouhal number analytical solutions to the compressible Stokes layer problem are deduced and shown to be in better agreement with numerical solutions compared to previous works. The adjoint methodology of Hill in the context of acoustic receptivity is extended to the compressible flow regime and an alternative formulation to predict sensitivity to the angle of incidence of an acoustic wave is proposed. Good agreement of the acoustic AHLNS receptivity model is found with published direct numerical simulations and the simpler finite Reynolds number approach. Parametric investigations of the influence of the acoustic wave angle on receptivity amplitudes reveal that the linearised unsteady boundary layer equations are a valid model of the acoustic signature for a large range of acoustic wave obliqueness values, failing only where the wave is highly oblique and travels upstream. An extensive parametric study of the influence of frequency, spanwise wavenumber, local Reynolds number and free-stream Mach number over the efficiency function for the different types of wall perturbation mechanisms is undertaken.

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Section: Introductionmentioning

confidence: 99%

An adjoint compressible linearised Navier–Stokes approach to model generation of Tollmien–Schlichting waves by sound

2019

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“…It has become widely accepted that for Tu smaller than approximately 0.1 %, transition occurs as a result of the excitation of Tollmien-Schlichting (TS) waves through receptivity, i.e. the mechanism by which disturbances penetrate the boundary layer and become unstable (Goldstein 1983;Ruban 1984Ruban , 1985Goldstein 1985;Reed, Reshotko & Saric 2015). For Tu larger than approximately 1 %, transition instead occurs earlier and the TS-wave scenario only plays a secondary role.…”

Section: Boundary-layer Flowsmentioning

confidence: 99%

Entrainment and growth of vortical disturbances in the channel-entrance region

Riccó

Alvarenga

2021

J. Fluid Mech.

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The entrainment of free-stream unsteady three-dimensional vortical disturbances in the entry region of a channel is studied via matched asymptotic expansions and by numerical means. The interest is in flows at Reynolds numbers where experimental studies have documented the occurrence of intense transient growth, despite the flow being stable according to classical stability analysis. The analytical description of the vortical perturbations at the channel mouth reveals how the oncoming disturbances penetrate into the wall-attached shear layers and amplify downstream. The effects of the channel confinement, the streamwise pressure gradient and the viscous/inviscid interplay between the oncoming disturbances and the boundary-layer perturbations are discussed. The composite perturbation velocity profiles are employed as initial conditions for the unsteady boundary-region perturbation equations. At a short distance from the channel mouth, the disturbance flow is mostly confined within the shear layers and assumes the form of streamwise-elongated streaks, while farther downstream the viscous disturbances permeate the whole channel although the base flow is still mostly inviscid in the core. Symmetrical disturbances exhibit a more significant growth than anti-symmetrical disturbances, the latter maintaining a nearly constant amplitude for several channel heights downstream before growing transiently, a unique feature not reported in open boundary layers. The disturbances are more intense as the frequency decreases or the bulk Reynolds number increases. We compute the spanwise wavelengths that cause the most intense downstream growth and the threshold wall-normal wavelengths below which the perturbations are damped through viscous dissipation.

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“…Receptivity is the process by which such disturbances couple to produce the initial disturbance amplitudes within the boundary layer which then grow and eventually break down to turbulence. Reed & Saric (2015) provides historical review of the concept of receptivity as well as a summary of modern progress in receptivity understanding for subsonic/transonic flight regimes. As noted before, traveling crossflow is predicted to have higher growth rates than its stationary counterpart but is not observed to be the dominant mechanism in flows with a low disturbance environment.…”

Section: Crossflow Instabilitymentioning

confidence: 99%

“…The semicircular arc which defines the nosetip results in at a discontinuity in curvature at the junction between the nosetip and the elliptic cone frustum (Choudhari et al, 2009). Such discontinuity has been shown to be a source of receptivity in low-speed flows (Lin et al, 1992;Saric et al, 2002;Reed & Saric, 2015). Instead of a circular arc, the nosetip of the model constructed and utilized in this campaign is defined by a modified super ellipse which eliminates this discontinuity.…”

Section: Elliptic Nose Tipmentioning

confidence: 99%

Influence of Environmental Disturbances on Hypersonic Crossflow Instability on the HIFiRE-5 Elliptic Cone

Neel

Leidy

Tichenor

et al. 2018

2018 AIAA Aerospace Sciences Meeting

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Crossflow instabilities on a 2:1 elliptic cone in hypersonic flow have been investigated in the M6QT and ACE wind tunnels at the Texas A&M National Aerothermochemistry and Hypersonics Laboratory. Experiments on a PEEK 38.1% scale model of the HIFiRE-5 flight test geometry were conducted to investigate the development of crossflow instabilities as well as to characterize the freestream and surface conditions responsible for their initial amplitudes. The freestream environment was varied not only by testing the model in both quiet and conventional tunnels but also by passively changing the fluctuation levels experienced in the conventional facility through systematic model placement. ACE freestream measurements, using a Kulite pressure transducer mounted in a pitot probe configuration and a hot-wire anemometer, indicated that fluctuation levels at the upstream model station were half those at the downstream stations. Fast-response PCB and Kulite surface mounted pressure transducers allowed examination of pressure fluctuation amplitudes and

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Receptivity: The Inspiration of Mark Morkovin (Invited)

Cited by 13 publications

References 94 publications

An adjoint compressible linearised Navier–Stokes approach to model generation of Tollmien–Schlichting waves by sound

An adjoint compressible linearised Navier–Stokes approach to model generation of Tollmien–Schlichting waves by sound

Entrainment and growth of vortical disturbances in the channel-entrance region

Influence of Environmental Disturbances on Hypersonic Crossflow Instability on the HIFiRE-5 Elliptic Cone

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