Synthetic generation of equilibrium boundary layer turbulence from modeled statistics

Adler, Michael C.; González, David R.; Stack, Cory M.; Gaitonde, Datta V.

doi:10.1016/j.compfluid.2018.01.003

Cited by 57 publications

(17 citation statements)

References 51 publications

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“…Details of the numerical discretization, boundary conditions, and mean-flow validation for the current database are well documented in previous publications [2,[4][5][6]8] and are therefore treated with brevity. The computational grids are described in Table 3 and comprise 8.9 × 10 7 -2.6 × 10 8 total points, with near wall resolution…”

Section: Simulation Methodsmentioning

confidence: 99%

“…Synthetic turbulence is introduced on the inflow boundary using a digital filtering procedure. Considerations arising from the use of modeled statistics using RANS simulations, as opposed to available simulated DNS data, and other aspects such as streamwise lengths required to establish convergence of inner and outer scales have been outlined in Adler et al [8]. These observations are employed to choose a distance of 18δ upstream of the geometric origin to allow for development of the incoming turbulent boundary layer.…”

Section: Simulation Methodsmentioning

confidence: 99%

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Influence of separation structure on the dynamics of shock/turbulent-boundary-layer interactions

Adler

Gaitonde

2021

Theor. Comput. Fluid Dyn.

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Shock/turbulent-boundary-layer interactions (STBLIs) are ubiquitous in high-speed flight and propulsion applications. Experimental and computational investigations of swept, three-dimensional (3-D) interactions, which exhibit quasi-conical mean-flow symmetry in the limit of infinite span, have demonstrated key differences in unsteadiness from their analogous, two-dimensional (2-D), spanwise-homogeneous counterparts. For swept interactions, represented by the swept–fin-on-plate and swept–compression–ramp-on-plate configurations, differences associated with the separated shear layers may be traced to the intermixing of 2-D (spanwise independent) and 3-D (spanwise dependent) scaling laws for the separated mean flow. This results in a broader spectrum of unsteadiness that includes relatively lower frequencies associated with the separated shear layers in 3-D interactions. However, lower frequency ranges associated with the global “breathing” of strongly separated 2-D interactions are significantly less prominent in these simple, swept 3-D interactions. A logical extension of 3-D interaction complexity is the compound interaction formed by the merging of two simple interactions. The first objective of this work is therefore to analyze the more complex picture of the dynamics of such interactions, by considering as an exemplar, wall-resolved simulations of the double-fin-on-plate configuration. We show that in the region of interaction merging, new flow scales, changes in separation topology, and the emergence of lower-frequency phenomena are observed, whereas the dynamics of the interaction near the fin leading edges are similar to those of the simple, swept interactions. The second objective is to evolve a unified understanding of the dynamics of STBLIs associated with complex configurations relevant to actual propulsion systems, which involve the coupling between multiple shock systems and multiple flow separation and attachment events. For this, we revisit the salient aspects of scaling phenomena in a manner that aids in assimilating the double-fin flow with simpler swept interactions. The emphasis is on the influence of the underlying structure of the separated flow on the dynamics. The distinct features of the compound interactions manifest in a centerline symmetry pattern that replaces the quasi-conical symmetry of simple interactions. The primary separation displays topological closure to reveal new length scales, associated unsteadiness bands, and secondary flow separation.

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Section: Simulation Methodsmentioning

confidence: 99%

Section: Simulation Methodsmentioning

confidence: 99%

Influence of separation structure on the dynamics of shock/turbulent-boundary-layer interactions

Adler

Gaitonde

2021

Theor. Comput. Fluid Dyn.

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“…No explicit subgrid scale (SGS) turbulence model is employed, because the described high-order numerical scheme with comparable grid resolution has proven effective for the simulation of supersonic boundary layers and STBLIs [7,[50][51][52]. When using such a scheme, the inclusion of an explicit SGS model introduces excessive artificial dissipation, as demonstrated by Kawai et al [53].…”

Section: A Governing Equations and Numerical Methodsmentioning

confidence: 99%

“…The turbulent boundary layer is introduced at the inflow plane via a RANS-initialized synthetic-digital-filtering method (RI-SDFM) discussed extensively by Adler et al [52]. Properties are presented therein of a turbulent boundary layer with the same flow conditions, grid resolution, and numerical method considered in this study.…”

Section: B Geometry Computational Grid and Boundary Conditionsmentioning

confidence: 99%

Flow Similarity in Strong Swept-Shock/Turbulent-Boundary-Layer Interactions

Adler

Gaitonde

2019

AIAA Journal

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The separation length employed to scale unsteady phenomena in strong (separated) nominally two-dimensional (2-D) shock/turbulent-boundary-layer interactions cannot be directly extended to three-dimensional (3-D) swept interactions, due to the quasi-conical symmetry of 3-D interactions. This paper examines the issue by considering large-eddy simulations of Mach 2 canonical flows arising from plate-mounted swept compression ramps and sharp fins at various interaction strengths, which have been the subject of concurrent experimental campaigns. Several key structural features are discussed that distinguish 3-D interactions from 2-D interactions in the context of free-interaction principles and quasi-conical symmetry, including their relationship to strong crossflow and open separation. The virtual-conical-origin concept is augmented by considering inceptive effects, which motivate the introduction of an inceptive origin. The dependence of the inceptive-origin/virtual-conical-origin relationship with interaction strength yields several insights and provides a more rigorous framework to quantify inception strength than previously available. Finally, examination of the spanwise dependence of the growth of the quasi-conical separated shear layer shows that the outer (main) layer exhibits spanwise-homogeneous symmetry consistent with 2-D free-interaction theory, whereas the inner layer exhibits conical symmetry, consistent with 3-D (conical) free-interaction theory. The ramifications for shear layer and shock unsteadiness, as well as acceleration of the inner layer and secondary separation, are discussed. Recent developments and persisting fundamental challenges are discussed by Clemens and Narayanaswamy [2] and Gaitonde [3]. Significant insight has been gained through recent experimental and high-fidelity numerical efforts for canonical two-dimensional (2-D) configurations, which are spanwise homogeneous apart from side-wall effects. These include the impinging shock [4-7] and compression ramp [8,9] interactions. Comparatively less attention has been focused on the unsteady properties of canonical three-dimensional (3-D) STBLIs. These include configurations for which the mean flow is 3-D; that is, interactions that exhibit spanwise nonhomogeneity caused by the geometry/orientation of the shock generator which cannot be attributed to edge/side-wall effects. Specifically, interactions in which the shock or obstacle is swept with respect to the incoming flow are of interest. These include the sharp-fin (SF), swept-compression-ramp (SCR), and swept-impinging-shock (SIS) configurations, as commonly described [3,10]. Such interactions are of particular concern in application to supersonic/hypersonic inlets with side-wall compression, because side-wall compression may be exploited to increase the total pressure recovery [11,12]. More complex scenarios include flows with multiple interactions (shock trains) in scramjet inlet/ isolator sections, which highlight complexities associated with the dynamic coupling between canonical i...

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“…Although DNS databases are often employed to obtain the time-mean velocity and Reynolds stresses, in the present work, such a database is not available. Thus, modeled statistics from a much cheaper Reynolds Averaged Navier-Stokes (RANS) simulation with a k − turbulence model is used, following the practices outlined by Adler et al [41] to obtain an equilibrium turbulent boundary layer that interacts with the surface deformation. Far field boundary conditions are specified with first-order extrapolation of all variables on the downstream, top and side faces of the computational domain, while the bottom surface is a no-slip adiabatic wall.…”

Section: Flow Configurationmentioning

confidence: 99%

Spatially developing supersonic turbulent boundary layer subjected to static surface deformations

Shinde¹,

Becks²,

Deshmukh³

et al. 2021

European Journal of Mechanics - B/Fluids

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Synthetic generation of equilibrium boundary layer turbulence from modeled statistics

Cited by 57 publications

References 51 publications

Influence of separation structure on the dynamics of shock/turbulent-boundary-layer interactions

Influence of separation structure on the dynamics of shock/turbulent-boundary-layer interactions

Flow Similarity in Strong Swept-Shock/Turbulent-Boundary-Layer Interactions

Spatially developing supersonic turbulent boundary layer subjected to static surface deformations

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