Scale Resolving Simulations of the NASA Juncture Flow Model using the LAVA Solver

Ghate, Aditya S.; Housman, Jeffrey A.; Stich, Gerrit-Daniel; Kenway, Gaetan K.; Kiris, Cetin C.

doi:10.2514/6.2020-2735

Cited by 12 publications

(11 citation statements)

References 38 publications

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“…Direct comparison of these dimensions with oil-film experimental results show that the WMLES prediction is about 15% lower than the experimental measurements (120 × 80 mm), consistent with previous WMLES investigations [26][27][28].…”

Section: F Visualization Of the Separation Bubblesupporting

confidence: 88%

“…According to NASA's recent CFD Vision 2030 report [6], hybrid RANS/LES [23,24] and WMLES [25] are identified as the most viable approaches for predicting realistic flows at high Reynolds numbers in external aerodynamics. Previous attempts of WMLES of the NASA Juncture Flow include the works by Iyer and Malik [26], Ghate et al [27], and Lozano-Durán et al [28,29]. These studies highlighted the capabilities of WMLES to predict wall pressure, velocity and Reynolds stresses, especially compared with RANS-based methodologies.…”

Section: Introductionmentioning

confidence: 99%

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Performance of wall-modeled LES with boundary-layer-conforming grids for external aerodynamics

Lozano-Durán¹,

Bose²,

Moin³

2021

Preprint

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We investigate the error scaling and computational cost of wall-modeled large-eddy simulation (WMLES) for external aerodynamic applications. The NASA Juncture Flow is used as representative of an aircraft with trailing-edge smooth-body separation. Two gridding strategies are examined: i) constant-size grid, in which the near-wall grid size has a constant value and ii) boundary-layer-conforming grid (BL-conforming grid), in which the grid size varies to accommodate the growth of the boundary-layer thickness. Our results are accompanied by a theoretical analysis of the cost and expected error scaling for the mean pressure coefficient (𝐶 𝑝 ) and mean velocity profiles. The prediction of 𝐶 𝑝 is within less than 5% error for all the grids studied, even when the boundary layers are marginally resolved. The high accuracy in the prediction of 𝐶 𝑝 is attributed to the outer-layer nature of the mean pressure in attached flows. The errors in the predicted mean velocity profiles exhibit a large variability depending on the location considered, namely, fuselage, wing-body juncture, or separated trailing-edge. WMLES performs as expected in regions where the flow resembles a zero-pressure-gradient turbulent boundary layer such as the fuselage (< 5% error). However, there is a decline in accuracy of WMLES predictions of mean velocities in the vicinity of wing-body junctions and, more acutely, in separated zones. The impact of the propagation of errors from the underresolved wing leading-edge is also investigated. It is shown that BL-conforming grids enable a higher accuracy in wing-body junctions and separated regions due to the more effective distribution of grid points, which in turn diminishes the streamwise propagation of errors.

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Section: F Visualization Of the Separation Bubblesupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Performance of wall-modeled LES with boundary-layer-conforming grids for external aerodynamics

Lozano-Durán¹,

Bose²,

Moin³

2021

Preprint

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“…The figure also contains a depiction of the average length and width of the separation bubble, which are about 100 mm and 60 mm, respectively, for case C-D0.5. Direct comparison of these dimensions with oil-film experimental results show that the current WMLES prediction is about 15% lower than the experimental measurements (120 × 80 mm), consistent with previous WMLES investigations Iyer & Malik 2020;Ghate et al 2020). Nonetheless, note that the sizes of the separation zone from WMLES are obtained from the tangential wall-stress streamlines after the wall stress is averaged in time, whereas the experimental sizes are obtained from the pattern resulting from the oil-film time evolution.…”

Section: Separation Bubblesupporting

confidence: 86%

“…In the present study, we perform WM-LES of the NASA Juncture Flow. Other attempts of WMLES of the same flow configuration include the works by Iyer & Malik (2020), Ghate et al (2020), and. These authors highlighted the capabilities of WMLES for predicting wall pressure, velocity and Reynolds stresses, especially compared with RANS-based methodologies.…”

mentioning

confidence: 99%

Performance of wall-modeled LES for external aerodynamics in the NASA Juncture Flow

Lozano-Durán¹,

Bose²,

Moin³

2021

Preprint

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The use of computational fluid dynamics (CFD) for external aerodynamic applications has been a key tool for aircraft design in the modern aerospace industry. CFD methodologies with increasing functionality and performance have greatly improved our understanding and predictive capabilities of complex flows. These improvements suggest that Certification by Analysis (CbA) -prediction of the aerodynamic quantities of interest by numerical simulations (Clark et al. 2020) may soon be a reality. CbA is expected to narrow the number of wind tunnel experiments, reducing both the turnover time and cost of the design cycle. However, flow predictions from the state-of-the-art CFD solvers are still unable to comply with the stringent accuracy requirements and computational efficiency demanded by the industry. These limitations are imposed, largely, by the defiant ubiquity of turbulence. In the present work, we investigate the performance of wall-modeled large-eddy simulation (WMLES) to predict the mean flow quantities over the fuselage and wing-body junction of the NASA Juncture Flow Experiment (Rumsey et al. 2019).Computations submitted to previous AIAA Drag Prediction Workshops (Vassberg et al. 2008) have displayed large variations in the prediction of separation, skin friction, and pressure in the corner-flow region near the wing trailing edge. To improve the performance of CFD, NASA has developed a validation experiment for a generic full-span wing-fuselage junction model at subsonic conditions. The reader is referred to Rumsey et al. (2019) for a summary of the history and goals of the NASA Juncture Flow Experiment (see also Rumsey & Morrison 2016;. The geometry and flow conditions are designed to yield flow separation in the trailing edge corner of the wing, with recirculation bubbles varying in size with the angle of attack (AoA). The model is a full-span wing-fuselage body that was configured with truncated DLR-F6 wings, both with and without leading-edge horn at the wing root. The model has been tested at a chord Reynolds number of 2.4 million, and AoA ranging from -10 degrees to +10 degrees in the Langley 14-by 22-foot Subsonic Tunnel. An overview of the experimental measurements can be found in Kegerise et al. (2019). The main aspects of the planning and execution of the project are discussed by Rumsey (2018), along with details about the CFD and experimental teams.To date, most CFD efforts on the NASA Juncture Flow Experiment have been conducted using RANS or hybrid-RANS solvers. Lee et al. (2017) performed the first CFD analysis to aid the NASA Juncture Flow committee in selecting the wing configuration for the final experiment. Lee et al. (2018) presented a preliminary CFD study of the near wing-body juncture region to evaluate the best practices in simulating wind tunnel effects. Rumsey et al. (2019) used FUN3D to investigate the ability of RANS-based CFD

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“…As outlined in the NASA CFD Vision 2030 Study [2], RANS-based turbulence models have limited predictive accuracy when dealing with separated flows, complex flow interactions, etc. and there has been growing interest in methods which resolve some range of turbulence scales such as LES and hybrid RANS-LES [3,4].…”

Section: Introductionmentioning

confidence: 99%

The subgrid scale pressure field of scale-enriched Large Eddy Simulations using Gabor modes

D.¹,

Ghate²,

Lele³

2020

Preprint

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With the continuing progress in large eddy simulations (LES), and ever increasing computational resources, it is currently possible to numerically solve the time-dependent and anisotropic large scales of turbulence in a large variety of flows. For some applications this large-scale resolution is satisfactory. However, a wide range of engineering problems involve flows at very large Reynolds numbers where the subgrid scale dynamics of a practical LES are critically important to design and yet are out of reach given the computational demands of solving the Navier Stokes equations; this difficulty is particularly relevant in wall-bounded turbulence where even the large-scales are often below the implied filter width of modest cost wall modeled LES (WMLES). In this paper we briefly introduce a scale enrichment procedure which leverages spatially and spectrally-localized Gabor modes. The method provides a physically consistent description of the small scale velocity field without solving the full non-linear equations. The enrichment procedure is appraised against its ability to predict small scale contributions to the pressure field. We find that the method accurately extrapolates the pressure spectrum and recovers pressure variance of the full field remarkably well when compared to a computationally expensive, highly resolved LES. The analysis is conducted both in a priori and a posteriori settings for the case of homogeneous isotropic turbulence (HIT).

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Scale Resolving Simulations of the NASA Juncture Flow Model using the LAVA Solver

Cited by 12 publications

References 38 publications

Performance of wall-modeled LES with boundary-layer-conforming grids for external aerodynamics

Performance of wall-modeled LES with boundary-layer-conforming grids for external aerodynamics

Performance of wall-modeled LES for external aerodynamics in the NASA Juncture Flow

The subgrid scale pressure field of scale-enriched Large Eddy Simulations using Gabor modes

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