Implicit Large Eddy Simulations Using a High-Order Overset Grid Solver

Sherer, Scott E.; Visbal, Miguel R.

doi:10.2514/6.2004-2530

Cited by 20 publications

(6 citation statements)

References 25 publications

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“…These cases include the interpolation of various analytic test functions from one grid to another, and the twodimensional fluid dynamics problems of the convection of an inviscid vortex, the low-speed, laminar flow over one and two circular cylinders, and the scattering of acoustic waves from single-and three-cylinder configurations. While all of the fluid dynamics validation cases presented here are two-dimensional in nature, the method is completely extendable to three spatial dimensions as is demonstrated in [23].…”

Section: Introductionmentioning

confidence: 92%

High-order compact finite-difference methods on general overset grids

Sherer

Scott

2005

Journal of Computational Physics

238

120

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Section: Introductionmentioning

confidence: 92%

High-order compact finite-difference methods on general overset grids

Sherer

Scott

2005

Journal of Computational Physics

238

120

View full text Add to dashboard Cite

“…46,47 The mesh was decomposed into a set of 256 overlapped sub-domains or blocks which were assigned to individual processors. A fivepoint inter-block overlap was employed in order to retain high-order numerical accuracy.…”

Section: A Details Of Computationsmentioning

confidence: 99%

Flow Structure and Unsteady Loading over a Pitching and Perching Low-Aspect-Ratio Wing

Visbal

2012

42nd AIAA Fluid Dynamics Conference and Exhibit

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This study addresses the flow structure and unsteady loading arising over a low-aspect-ratio rectangular wing subjected to high-amplitude pitching and perching maneuvers under low-Reynolds-number conditions of interest in small unmanned aerial vehicle operation and gust interactions. Simulations are performed employing an extensively-validated high-fidelity computational approach capable of accurately capturing the complex unsteady transitional flows. Canonical pitching motions for a non-translating wing in the presence of a constant freestream are first investigated in order to elucidate the effects of pitch rate and Reynolds number on the flow structure and aerodynamic loading. The wing is pitched about its quarter-chord axis to a maximum incidence of 45 • with nominal non-dimensional angular rates 0.05 ≤ Ω + ≤ 0.2. The Reynolds number based on the wing chord varied from 10 3 to 4 × 10 4 . For the highest pitch rate, good agreement between the computed three-dimensional flow structure and recent experimental measurements is demonstrated. The 3D dynamic stall process is characterized by the formation of an initial spanwise-oriented leading-edge vortex which evolves into an arch-type structure with legs anchored on the wing surface. This dominant flow element of low-aspect-ratio wings exhibits a long residence time and establishes a well-defined low-pressure region and swirling pattern on the wing surface. Increasing pitch rate promotes an angular delay in the flow evolution and corresponding aerodynamic loads. Even for the lowest pitch rate, a significant increase in maximum lift is achieved relative to the static situation. The low-aspect-ratio of the wing also promotes further delay of dynamic stall and a much smoother behavior of the aerodynamic coefficients when compared to a pitching 2D wing section. The formation of the arch vortex and swirling pattern are found to be qualitatively similar over the range of Reynolds number studied. At fixed pitch rate, higher Reynolds number promotes a more compact arch vortex, a stronger suction on the wing and further stall delay. Canonical perching maneuvers involving simultaneous rotation and deceleration to rest are considered at two values of pitch rate. The reduction in translating velocity halts the development of the leading-edge vortex system which eventually moves upstream in front of the wing. Attempts to correlate the perching loads with the constant-freestream pitching cases indicate that agreement can only be achieved for the initial portion of the maneuver. Discrepancies arise at high angles of attack which depend on the value of pitch rate itself. Nomenclature c = wing chord C L , C D , C M = lift, drag and quarter-chord pitching moment coefficients C Lo , C Do , C M o = non-dimensional lift, drag and pitching moment for perching wing C Lw , C Dw , C M w = lift, drag and pitching moment for perching wing rescaled with translational velocityviscous vector fluxes J = Jacobian of the coordinate transformation LEV = leading-edge vortex M = Mach number p = stat...

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“…They also showed that the use of an SGS model in those simulations did not produce results superior to those obtained without employing an SGS model. The ILES approach has been successfully used by Sherer and Visbal 28 in turbulent channel flow computations as well.…”

Section: Computational Methodologymentioning

confidence: 99%

Noise Generation in the Near-Nozzle Region of a Chevron Nozzle Jet Flow

Uzun

Hussaini

2007

13th AIAA/CEAS Aeroacoustics Conference (28th AIAA Aeroacoustics Conference)

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This paper reports on the simulation of the near-nozzle region of a moderate Reynolds number cold jet flow exhausting from a chevron nozzle. The chevron nozzle considered in this study is the SMC001 nozzle experimentally studied by the researchers at the NASA Glenn Research Center. This nozzle design contains six symmetric chevrons that have a five-degree penetration angle. The flow inside the chevron nozzle and the free jet flow outside are computed simultaneously by a high-order accurate, multi-block, large eddy simulation (LES) code with overset grid capability. The total number of grid points at which the governing equations are solved is about 100 million. The main emphasis of the simulation is to capture the enhanced shear layer mixing due to the chevrons and the consequent noise generation that occurs in the mixing layers of the jet within the first few diameters downstream of the nozzle exit. Details of the computational methodology are presented together with an analysis of the simulation results. The simulation data are compared with available experimental flow field measurements for the same nozzle geometry. A comparison of the noise spectrum in the sideline direction with experimental data is also carried out. Overall, the simulation results are very encouraging and demonstrate the feasibility of chevron nozzle jet computations using our simulation methodology.

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Implicit Large Eddy Simulations Using a High-Order Overset Grid Solver

Cited by 20 publications

References 25 publications

High-order compact finite-difference methods on general overset grids

High-order compact finite-difference methods on general overset grids

Flow Structure and Unsteady Loading over a Pitching and Perching Low-Aspect-Ratio Wing

Noise Generation in the Near-Nozzle Region of a Chevron Nozzle Jet Flow

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