Comprehensive mesh study for a Direct Numerical Simulation of the transonic flow at Rec = 500,000 around a NACA 0012 airfoil

Gageik, Manuel; Klioutchnikov, Igor; Olivier, H.

doi:10.1016/j.compfluid.2015.08.030

Cited by 14 publications

(6 citation statements)

References 14 publications

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“…A clear convergence can be seen as the mesh is refined, particularly when the pure central scheme is considered. Interestingly, the overprediction of k at low wavenumbers is also seen in a recent DNS study, 49 where simulations of the flow over a NACA0012 are performed at a Reynolds number of 500 000. The aim of the study is to assess the grid convergence.…”

Section: B Effect Of Mesh Resolution and Discretization Schemesupporting

confidence: 59%

Boundary layer transition over a foil using direct numerical simulation and large eddy simulation

Smith

Ventikos

2019

Physics of Fluids

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Transitional boundary layers over lifting bodies represent an important class of flows in many industrial applications, and accurately capturing the transition is crucial for the prediction of important phenomena such as lift, drag, and trailing-edge noise. In this study, we consider how large eddy simulations (LESs) can be used to capture the natural boundary layer transition and compare the results to fully resolved direct numerical simulations that provide a detailed picture of the transition and trailing edge flow. The ability of LES to capture the transition is considered by looking at different elements of the subfilter scale modeling and discretization. The behavior of the subfilter scale model is shown to be critical, and it must remain inactive during the early stages of transition to avoid erroneous predictions due to excessive dissipation. Dispersion errors, when present, can cause the natural transition mechanism to be bypassed at an earlier stage, which leads to higher levels of turbulent kinetic energy at the trailing edge.

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Section: B Effect Of Mesh Resolution and Discretization Schemesupporting

confidence: 59%

Boundary layer transition over a foil using direct numerical simulation and large eddy simulation

Smith

Ventikos

2019

Physics of Fluids

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“…An extensive grid dependency study confirmed the grid independence of all discussed flow phenomena, suggesting a sufficiently resolved flowfield for the reference case. This is supported by the partially converged grid study of [16],…”

Section: Discussionmentioning

confidence: 59%

“…Considering a low Mach number of M = 0.2, [14] pushed the Reynolds number for a 3D DNS of a NACA0012 airfoil to micro air vehicle (MAV) conditions, whereas [15] considered Mach-and Reynolds-numbers up to M = 0.8 and Re = 50,000, respectively. An extensive grid dependency study of the well known NACA0012 airfoil was conducted by [16] for a moderate Reynolds number of Re = 500,000…”

Section: Nomenclaturementioning

confidence: 99%

Direct Numerical Simulations of Transonic Flow Around an Airfoil at Moderate Reynolds Numbers

2019

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In order to reduce friction and wave drag on the wings of more efficient next generation aircraft, it is important to understand laminar-turbulent boundary-layer transition and shockwave interactions. In this contribution, fully-resolved direct numerical simulations of Dassault Aviation's V2C profile at transonic conditions and a Reynolds number of half a million are presented. Kelvin-Helmholtz instabilities appear in the shear layers on the pressure-and suction-sides, followed by a self-sustained laminar-turbulent transition process promoted by the stretching of rib vortices between larger co-rotating structures. Multiple acoustic structures interacting with the boundary layer are also observed, together with upstream-propagating shock waves. Regions of flow separation on the suction side exhibit unsteadiness with Strouhal numbers in the range of St ≈ 0.5 − 0.6. This is distinct from a standing wave oscillation in lift at St = 0.12, which agrees well with transonic buffet frequencies, reported for experiments on the same airfoil at higher Reynolds numbers. The insensitivity of the principal results to the chosen grid resolution and spanwise domain size is carefully established.

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“…DNSs have been used to provide very detailed insights into the flow physics of infinite-span wing flows, [53][54][55][56] and it is hoped that a similar level of detail and understanding can be achieved here for the flow over a finite-span wing. Due to the lack of detailed experimental data for near-field wing-tip vortex studies at low and moderate Reynolds numbers, we use three different grids for each Reynolds number in order to assess the level of grid convergence.…”

Section: Introductionmentioning

confidence: 99%

Wing-tip vortex dynamics at moderate Reynolds numbers

Smith

Ventikos

2021

Physics of Fluids

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The flow over a flat-tipped wing at three Reynolds numbers: Re ¼ 1 Â 10 4 ; Re ¼ 4 Â 10 4 , and Re ¼ 1 Â 10 5 is investigated using direct numerical simulation. A set of grid independent results are obtained which allow for the dynamics of the tip flow, trailing vortices, and their interplay with the boundary layer dynamics to be examined in detail. The results show significant changes across the Reynolds number range. At the lowest Reynolds number, a single trailing vortex forms downstream of the trailing edge, whereas multiple vortices form over the tip at higher Reynolds numbers. The tip geometry is shown to be important with regard to the development of different structures and in the transition of the flow from laminar to turbulent. This is due to unstable shear layers, with turbulent flow becoming entrained in the vortex cores at higher Reynolds numbers. These changing vortex dynamics mean that the value of the minimum vortex core pressure and its location change with Reynolds number. This has important consequences for cavitation inception and scaling for hydrodynamic applications. The influence of the tip flow on the boundary layer is further considered by comparing the flow with that of an infinite-span wing. Analysis of the two cases shows that the tip flow reduces the effective angle of attack, which prevents the flow separation at the leading edge that is responsible for the boundary layer transition for the infinite-span case. This, in turn, changes the character of the trailing edge flow which would have significant consequences on the trailing edge noise.

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Comprehensive mesh study for a Direct Numerical Simulation of the transonic flow at Rec = 500,000 around a NACA 0012 airfoil

Cited by 14 publications

References 14 publications

Boundary layer transition over a foil using direct numerical simulation and large eddy simulation

Boundary layer transition over a foil using direct numerical simulation and large eddy simulation

Direct Numerical Simulations of Transonic Flow Around an Airfoil at Moderate Reynolds Numbers

Wing-tip vortex dynamics at moderate Reynolds numbers

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