Detached-Eddy Simulations of a Full-Span Delta Wing at High Incidence

Görtz, Stefan

doi:10.2514/6.2003-4216

Cited by 11 publications

(7 citation statements)

References 6 publications

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“…2 should have a non-dimensional time step of Dt * p0.025, a value which was used in the initial DES computations of Strelets [9]. This validates the earlier time-step results for similar flow fields [8][9][10], but also points out that there should be a general ''rule of thumb'' for the choice of time step: the time step should be determined by the temporal aspects of the flow feature(s) of interest in the computation. For example, Table 1 shows Strouhal numbers ranging from 0.01pStp10+, so it might be possible to use a much higher time step than Dt * ¼ 0.025, depending on the flow features of interest.…”

Section: Physical Time Step For Delta Wing Flow Computationssupporting

confidence: 59%

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Experiences in accurately predicting time-dependent flows

Cummings

Morton

McDaniel

2008

Progress in Aerospace Sciences

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As computational fluid dynamics matures, researchers attempt to perform numerical simulations on increasingly complex aerodynamic flows. One type of flow that has become feasible to simulate is massively separated flow fields, which exhibit high levels of flow unsteadiness. While traditional computational fluid dynamic approaches may be able to simulate these flows, it is not obvious what restrictions should be followed in order to insure that the numerical simulations are accurate and trustworthy. Our research group has considerable experience in computing massively separated flow fields about various aircraft configurations, which has led us to examine the factors necessary for making high-quality time-dependent flow computations. The factors we have identified include: grid density and local refinement, the numerical approach, performing a time-step study, the use of sub-iterations for temporal accuracy, the appropriate use of temporal damping, and the use of appropriate turbulence models. We have a variety of cases from which to draw results, including delta wings and the F-18C, F-16C, and F-16XL aircraft. Results show that while it is possible to obtain accurate unsteady aerodynamic computations, there is a high computational cost associated with performing the calculations. Rules of thumb and possible shortcuts for accurate prediction of massively separated flows are also discussed.

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Section: Physical Time Step For Delta Wing Flow Computationssupporting

confidence: 59%

“…Go¨ rtz [10] found that a time step of approximately Dt * ¼ 0.006 was required for accurate prediction of vortex breakdown over a delta wing at high angles of attack. Another study of high angle-of-attack flow over a delta wing by Schiavetta et al [11] showed good results with a time step of Dt * ¼ 0.01.…”

Section: How Small a Time Step? How Fine A Grid?mentioning

confidence: 99%

Experiences in accurately predicting time-dependent flows

Cummings

Morton

McDaniel

2008

Progress in Aerospace Sciences

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“…Recently, Morton et al [1], Morton [2], and Görtz [3] investigated the detached eddy simulation (DES) approach for improved prediction of the unsteady, vortical flowfields over delta wings. DES employs a traditional Reynolds-averaged Navier-Stokes turbulence model (Spallart-Allmaras) to represent the assumed turbulent wall boundary layer.…”

Section: Introductionmentioning

confidence: 99%

“…The model then smoothly switches to a large eddy simulation (LES)-like model (Smagorinsky) in the separated region to more accurately represent the separated flow. The DES approach has been implemented into standard second-order-accurate flow codes [1,3]. In this paper, an alternative implicit large eddy simulation (ILES) approach is employed, which is based on a sixth-orderaccurate computational scheme coupled with higher-order, low-pass filtering.…”

Section: Introductionmentioning

confidence: 99%

Computational and Experimental Investigation of a Nonslender Delta Wing

Gordnier¹,

Visbal²,

Gursul³

et al. 2009

AIAA Journal

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Computational simulations have been performed for a 50-deg-sweep delta wing with a sharp leading edge at a 15 deg angle of attack and moderate Reynolds numbers of Re 2 10 5 , Re 6:2 10 5 , and Re 2 10 6 . A sixthorder compact-difference scheme with an eighth-order low-pass filter is used to solve the Navier-Stokes equations. Turbulence modeling has been accomplished using an implicit large eddy simulation method that exploits the highorder accuracy of the compact-difference scheme and uses the discriminating higher-order filter to regularize the solution. Computations have been performed on a baseline mesh of 11:3 10 6 grid points and a refined mesh of 35 10 6 grid points. An assessment of grid resolution showed that significantly finer-scale features of the flow could be captured on the refined mesh, providing a more accurate representation of the complex, unsteady, separated flow. Comparisons are also made with high-resolution particle image velocimetry images obtained for the two lower Reynolds numbers. The numerical results are examined to provide a description of the mean and instantaneous flow structure over the delta wing, including the separated vortical flow, vortex breakdown, surface flow features, and surface boundary-layer transition near the symmetry plane. The effect of Reynolds number on each of these features is assessed.

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“…21 and G6rt [3] have investigated important Reynolds number effects for these complicated the Detached Eddy Simulation (DES) approach for transitional flowfields.…”

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confidence: 99%