An Investigation of Low-Reynolds-Number Flows Past Airfoils

Yuan, Weixing; Khalid, M.; Windte, Jan; Scholz, Ulrich; Radespiel, Rolf

doi:10.2514/6.2005-4607

Cited by 51 publications

(19 citation statements)

References 14 publications

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“…But at x/c=0.3, the amplitude of the Reynolds stress does not show a clear increase, so we take x/c=0.45 as the transition point in the present study. The transition point and reattachment point obtained are consistent with those in the literature [19,1]. However, the separation appears to occur earlier compared the numerical results in the literature.…”

Section: Flows Past a Stationary Airfoilsupporting

confidence: 94%

“…In this method, the transition point is defined as the beginning of the turbulent wedge that spreads from the shear layer of the LSB. Usually the point is taken where the normalized Reynolds shear stress is −0.001 and its amplitude demonstrates a clearly visible rise as is the case in other studies [19,1]. In the present study, the threshold of Reynolds stress is taken as −0.005 rather than −0.001.…”

Section: Flows Past a Stationary Airfoilmentioning

confidence: 95%

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Large-eddy simulation of flows past a flapping airfoil using immersed boundary method

Yang

Zhang

2010

Sci. China Phys. Mech. Astron.

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The numerical simulation of flows past flapping foils at moderate Reynolds numbers presents two challenges to computational fluid dynamics: turbulent flows and moving boundaries. The direct forcing immersed boundary (IB) method has been developed to simulate laminar flows. However, its performance in simulating turbulent flows and transitional flows with moving boundaries has not been fully evaluated. In the present work, we use the IB method to simulate fully developed turbulent channel flows and transitional flows past a stationary/plunging SD7003 airfoil. To suppress the non-physical force oscillations in the plunging case, we use the smoothed discrete delta function for interpolation in the IB method. The results of the present work demonstrate that the IB method can be used to simulate turbulent flows and transitional flows with moving boundaries. transitional flows, moving boundary, immersed boundary method, smoothed discrete delta function

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Section: Flows Past a Stationary Airfoilsupporting

confidence: 94%

Section: Flows Past a Stationary Airfoilmentioning

confidence: 95%

Large-eddy simulation of flows past a flapping airfoil using immersed boundary method

Yang

Zhang

2010

Sci. China Phys. Mech. Astron.

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“…It is known that the drag-polar and lift curve slope of airfoils at Re < 10 5 are noticeably affected by laminar separation, exhibiting the so-called drag bulge. Efforts are being made experimentally and computationally to investigate low Reynolds number transition [22][23][24][25][26]. Transition and leading edge vortex breakdown in biological flyers have not been adequately studied.…”

Section: Aerodynamics and Flapping Kinematicsmentioning

confidence: 99%

Computational aerodynamics of low Reynolds number plunging, pitching and flexible wings for MAV applications

et al. 2008

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Micro air vehicles (MAV's) have the potential to revolutionize our sensing and information gathering capabilities in environmental monitoring and homeland security areas. Due to the MAV's' small size, flight regime, and modes of operation, significant scientific advancement will be needed to create this revolutionary capability. Aerodynamics, structural dynamics, and flight dynamics of natural flyers intersects with some of the richest problems in MAV's, including massively unsteady three-dimensional separation, transition in boundary layers and shear layers, vortical flows and bluff body flows, unsteady flight environment, aeroelasticity, and nonlinear and adaptive control are just a few examples. A challenge is that the scaling of both fluid dynamics and structural dynamics between smaller natural flyer and practical flying hardware/lab experiment (larger dimension) is fundamentally difficult. In this paper, we offer an overview of the challenges and issues, along with sample results illustrating some of the efforts made from a computational modeling angle.

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“…Therefore, these two models were further applied to a static SD7003 airfoil at Re c 60; 000 and α 4 deg. Both models have proven to be able to model the transition process over a laminar separation bubble of airfoils at low Reynolds numbers at low turbulence intensity, as shown in Table 1 and [24], while the NRC's 3-D LES and quasi 3-D Launder-Sharma k-ε model results can be found in [23] and [25], respectively. In Table 1, x s , x t , and x r represent the locations of initial laminar separation, laminar-turbulent transition, and turbulent reattachment.…”

Section: B Transition Modelingmentioning

confidence: 99%

Effect of Freestream Turbulence on Airfoil Limit-Cycle Oscillations at Transitional Reynolds Numbers

Yuan

Poirel

Wang

et al. 2015

Journal of Aircraft

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Numerical simulations are performed to study the effect of freestream turbulence on small-amplitude limit-cycle oscillations of an airfoil at transitional Reynolds numbers. A one-degree-of-freedom aeroelastic model was coupled with the National Research Council Canada in-house computational-fluid-dynamics code INSflow to perform unsteady Reynolds-averaged Navier-Stokes simulations for flows around a rigid NACA 0012 airfoil in free-to-rotate conditions. Without coupling a transition model, unsteady Reynolds-averaged Navier-Stokes computations based on the commonly used shear-stress-transport turbulence model could not capture the limit-cycle oscillations. This was expected because it had been previously shown that the limit-cycle oscillations were fed by negative aerodynamic damping due to laminar boundary-layer separation. A correlation-based transition model was then implemented in the code and applied to investigate the turbulence effects. The computed results confirmed qualitatively the experimental observations of the turbulence effects on the limit-cycle oscillations by varying the values of the turbulence intensity and length scale. It was observed that the limit-cycle oscillations were more sensitive to the turbulence intensity than to the latter. In general, the freestream turbulence suppressed the limit-cycle oscillations. The pitch amplitude became smaller when the freestream turbulence intensity was increased, which was qualitatively in good agreement with experimental results. The limit-cycle oscillations could not be sustained when the input freestream turbulence level reached around 1.25%. An examination of the unsteady flowfield revealed that the freestream turbulence affected the location of the separation points and suppressed the laminar-turbulent transition process.

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An Investigation of Low-Reynolds-Number Flows Past Airfoils

Cited by 51 publications

References 14 publications

Large-eddy simulation of flows past a flapping airfoil using immersed boundary method

Large-eddy simulation of flows past a flapping airfoil using immersed boundary method

Computational aerodynamics of low Reynolds number plunging, pitching and flexible wings for MAV applications

Effect of Freestream Turbulence on Airfoil Limit-Cycle Oscillations at Transitional Reynolds Numbers

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