DNS database of a transitional separation bubble on a flat plate and application to RANS modeling validation

Laurent, Claire; Mary, Ivan; Gleize, Vincent; Lerat, A.; Arnal, D.

doi:10.1016/j.compfluid.2011.07.011

Cited by 32 publications

(29 citation statements)

References 17 publications

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“…The cell sizes are on the upper side, downstream of the shock x + = 25, y + = 1, z + = 5 (close to a direct numerical simulation (DNS) resolution and better than usual LES resolutions) and on the lower side x + = 46, y + = 1, z + = 15 (classical LES resolution). The effect of the grid resolution on the turbulence statistics has not been assessed on the present case but on a similar one (transitional separation bubble, see Laurent et al (2012)). Five grid densities were compared and the results were considered as converged on the 60 million cell grid which had a resolution x + = 27, y + = 1, z + = 5, close the present one on the suction side.…”

Section: Methodsmentioning

confidence: 94%

“…Yang & Voke (2001) reported St L between 0.52 and 1.14 (or St δ * S = 0.005 to 0.011) for the bubble bursting phenomenon. In Laurent et al (2012), St L is equal to 2.7 (St δ * S = 0.12). Marquillie & Ehrenstein (2003) have studied numerically the effect of the Reynolds number on the flow at the rear of a two-dimensional bump mounted on a flat plate.…”

Section: Introductionmentioning

confidence: 99%

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Large-eddy simulation of laminar transonic buffet

2018

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A large-eddy simulation of laminar transonic buffet on an airfoil at a Mach number $M=0.735$, an angle of attack $\unicode[STIX]{x1D6FC}=4^{\circ }$, a Reynolds number $Re_{c}=3\times 10^{6}$ has been carried out. The boundary layer is laminar up to the shock foot and laminar/turbulent transition occurs in the separation bubble at the shock foot. Contrary to the turbulent case for which wall pressure spectra are characterised by well-marked peaks at low frequencies ($St=f\cdot c/U_{\infty }\simeq 0.06{-}0.07$, where $St$ is the Strouhal number, $f$ the shock oscillation frequency, $c$ the chord length and $U_{\infty }$ the free-stream velocity), in the laminar case, there are also well-marked peaks but at a much higher frequency ($St=1.2$). The shock oscillation amplitude is also lower: 6 % of chord and limited to the shock foot area in the laminar case instead of 20 % with a whole shock oscillation and intermittent boundary layer separation and reattachment in the turbulent case. The analysis of the phase-averaged fields allowed linking of the frequency of the laminar transonic buffet to a separation bubble breathing phenomenon associated with a vortex shedding mechanism. These vortices are convected at $U_{c}/U_{\infty }\simeq 0.4$ (where $U_{c}$ is the convection velocity). The main finding of the present paper is that the higher frequency of the shock oscillation in the laminar regime is due to a different mechanism than in the turbulent one: laminar transonic buffet is due to a separation bubble breathing phenomenon occurring at the shock foot.

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Section: Methodsmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Large-eddy simulation of laminar transonic buffet

2018

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“…Thanks to this technique, identical turbulent inflows feed both the ribbed wall simulations and their associated smooth surface reference ones, allowing a rigorous comparison of the results. More details and validation test cases of the solver are provided in [29,30].…”

Section: Methodsmentioning

confidence: 99%

Riblet Flow Model Based on an Extended FIK Identity

Bannier

Garnier

Sagaut

2015

Flow Turbulence Combust

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International audienceLarge Eddy Simulations of zero-pressure-gradient turbulent boundary layers over riblets have been conducted. All along the controlled domain, riblets maintain a significant 11 % drag reduction with respect to the flat plate at the same R e τ (from 250 to 450). To compare the flows above riblets and a reference smooth wall, an appropriate vertical shift between the two surfaces is required. In the present study, the “vertical origin” is set using the identity of Fukagata, Iwamoto and Kasagi (FIK) in Phys. Fluids, vol. 14, 2002, L73. This identity, which provides a physically meaningful decomposition of the skin friction, has been extended to complex wall surfaces and constitutes the basis for the derivation of a new virtual origin. Using this FIK-based origin, it is shown that the complex interactions between the riblets and the near-wall turbulent structures can be taken into account by a simple shift of the two axes of the mean and turbulent velocity profiles. The appropriate upward shift Δu +, typical for drag reduction, is directly dependent on the skin friction on the riblets and on the reference smooth plate at the same R e τ

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“…The triggering coefficients control the production of k and ω, and hence the growth of turbulence. They are calibrated to obtain the best possible agreement with available LSB DNS data [47,48]. Although most methods dealing with the transition region use the concept of intermittency [21,22], the transition-triggering functions used in the present work are not directly related to this concept, but should rather be considered as "empirical weighting coefficients" [49] designed to reproduce as best as possible the progressive growth of turbulence in LSBs.…”

Section: Introductionmentioning

confidence: 99%

Algebraic Nonlocal Transition Modeling of Laminar Separation Bubbles Using k−ω Turbulence Models

et al. 2019

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Algebraic transitional extensions for the accurate computation of laminar separation bubbles are developed for use with k-ω models. The transitional model, based on integral boundary-layer parameters and transition criteria, introduces streamwise-variable weighting of the production terms in the k-ω equations and delay of the shear-stresslimiter activation. Calibration to fit available DNS data yields satisfactory results for a flat-plate reference case, both for skin-friction and velocity-profiles. It is shown that the model can be adapted to different k-ω variants by appropriate calibration of coefficients. The model is then validated for 2 airfoil test-cases, both for very low and higher Reynolds numbers, a NACA 0012 airfoil at chord-based Reynolds number Re c = 10 5 and angle-of-attack α = 10.55 deg and a S809 airfoil at Re c = 2 × 10 6 and α = 1 deg. For both application cases comparison with available data is satisfactory. Nomenclature c = airfoil chord length (m) C lim = shear-stress limiter delay function Cp = pressure coefficient

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DNS database of a transitional separation bubble on a flat plate and application to RANS modeling validation

Cited by 32 publications

References 17 publications

Large-eddy simulation of laminar transonic buffet

Large-eddy simulation of laminar transonic buffet

Riblet Flow Model Based on an Extended FIK Identity

Algebraic Nonlocal Transition Modeling of Laminar Separation Bubbles Using k−ω Turbulence Models

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