Numerical simulation of flapping wings using a panel method and a high‐order Navier–Stokes solver

Persson, Per‐Olof; Willis, David J.; Peraire, J.

doi:10.1002/nme.3288

Cited by 30 publications

(31 citation statements)

References 52 publications

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“…As discussed in section II, the solver is similar to that used by other authors. [10][11][12][13] It should be noted that, besides their obvious limitations (inviscid, hence there is no skin friction and no separation), unsteady potential solvers have shown good agreement with experiments 13,14 and viscous simulations 12,15 for flapping wings at moderate Reynolds numbers (Re ≈ 10 3 − 10 4 ), reduced frequencies in the range 0.4 -3 and large flapping amplitudes (vertical displacement of the order of the chord of the wing). Additionally, the low computational cost of this solvers makes them excellent candidates for parametric sweeps, 16 or for optimization procedures.…”

Section: Introductionmentioning

confidence: 78%

“…To evaluate the relation between the increment in thrust and the increment in required power, figure 6 shows the propulsive efficiency, defined in eq. (12). First of all, the propulsive efficiencies reported in figure 6 are relatively low, around 50% for all cases considered here.…”

Section: Iiic Propulsive Efficiencymentioning

confidence: 85%

“…The wake configuration is similar to those obtained with unsteady panel methods for flapping wings at lower reduced frequencies, with and without twist. 11,12 On the other hand, the heaving case shows stronger vortex loops in the wake. Note that in figure 2(b) all the wake panels are concentrated on the lateral vortices, indicating a stronger roll-up of the wake around the wing tip vortices.…”

Section: Iiia Wake Topologymentioning

confidence: 93%

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Thrust generation in heaving and flapping wings in forward flight

Arranz

Flores

2016

34th AIAA Applied Aerodynamics Conference

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In this paper, we consider the effect of different flapping kinematics on the generation of aerodynamic forces in a pair of wings in forward flight. To this end, we use an unsteady panel method solver to perform a parametric study of three different parameters: the flapping radius, the reduced frequency, and the aspect ratio. Varying the flapping radius the motion of the wings smoothly changes from pure flapping (R = 0, rotation around the wing root) to heaving (R = ∞, vertical oscillation of the wings). The results indicate that the thrust generated increases with the flapping radius and the reduced frequency. However, the propulsive efficiency changes little with the radius of flapping (less than 2%), and remains roughly constant for R 2c. Only for small aspect ratios (AR = 1) the results show a slightly better propulsive efficiency for flapping with R ≈ 3c over heaving.

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Section: Introductionmentioning

confidence: 78%

Section: Iiic Propulsive Efficiencymentioning

confidence: 85%

Section: Iiia Wake Topologymentioning

confidence: 93%

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Thrust generation in heaving and flapping wings in forward flight

Arranz

Flores

2016

34th AIAA Applied Aerodynamics Conference

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“…They found that providing the wing morphing more flexibility (greater degrees of spatial and temporal freedom) improves the flapping wing design. In a recent paper, Persson et al (2012) conducted a detailed comparison between UVLM and higher-fidelity CFD methods for flapping flight. Their results indicated that the UVLM schemes produce accurate results for attached flow cases and even remain trend-relevant in the presence of flow separation.…”

Section: Introductionmentioning

confidence: 99%

Global optimization of actively morphing flapping wings

Ghommem

Hajj

Mook

et al. 2012

Journal of Fluids and Structures

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“…33 In three-dimensions, the analysis becomes a little more involved due to the increased number of degrees of freedom.…”

Section: Iiib Three-dimensional Geometry Definition and Computationalmentioning

confidence: 99%

Generating LEVs on Energetically Optimal, Flapping Wing Designs by Modulating Leading Edge Angle

Willis

Persson

2013

31st AIAA Applied Aerodynamics Conference

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In this paper a series of two-and three-dimensional, multi-fidelity computational models are presented and used in a preliminary exploration of leading edge vortex (LEV) evolution on pitching and plunging wings. The lower fidelity computational tools (thin airfoil theory and doublet lattice method) are framed in a quasi-inverse design context to determine the wing shape (twist and camber) that achieve a prescribed (leading and trailing edge) shed vorticity footprint. A high-order, computational fluid dynamics tool is used to simulate the final wing geometries.A series of preliminary results of increasing complexity and relevance to flapping wings are presented to demonstrate the viability of the lower fidelity quasi-inverse wing design methods. First a two-dimensional pitch-ramp case is presented to illustrate the impact of leading edge angle as well as leading and trailing edge vorticity shedding rate on the generation and persistence of LEVs. The second exploration considers a two-dimensional model of flapping downstroke motion (simple half cycle of a sinusoidal heave). Finally, some preliminary results using similar quasi-inverse design methods in three-dimensions are presented. While preliminary, the results of our investigations illustrate that LEVs can be modulated using an appropriate combination of wing local camber and incidence angle. I. BackgroundThe discovery of near wing flow structures (e.g. LEVs) on insect wings has revolutionized the fundamental comprehension of low-Reynolds number flapping flight. 1-6 Since their discovery, these near-wing flow structures have been examined and observed for insects using: observational animal-flight experiments, 1, 3, 7 physical laboratory experiments, 2, 5, 8-10 and computations. 11, 12 These studies have revealed insect-like flyers use leading and trailing edge flow structures to augment lift and improve maneuverability.The existence and role of LEV's in larger animals flying at moderate Reynolds numbers (e.g. bats and birds, Re 5, 000 − 50, 000 ) is less well understood. Until recently, it was not even clear whether these flyers employed LEVs for augmenting lift production. 13 In the past decade however, LEV structures have been observed in the laboratory for small and medium sized bats 14 and birds, 15, 16 indicating that these near-wing flow structures have some relevance in regimes other than insect flight. Most of the these observations have been made at slower flight speeds on actual animals.Because of the challenges associated with experimentally capturing LEVs during natural flight, much of the experimental and computational effort to understand their behavior has focused on LEV generation using prescribed geometries and prescribed kinematics. 2,11,12,17,18 These investigations explore the generation of LEVs on flat plates, insect wing models or flexible wings. While many of these studies have led to a deeper appreciation of LEV evolution, the experiments rely largely on the reaction of the fluid to the prescribed motion and prescribed shape of the imme...

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Numerical simulation of flapping wings using a panel method and a high‐order Navier–Stokes solver

Cited by 30 publications

References 52 publications

Thrust generation in heaving and flapping wings in forward flight

Thrust generation in heaving and flapping wings in forward flight

Global optimization of actively morphing flapping wings

Generating LEVs on Energetically Optimal, Flapping Wing Designs by Modulating Leading Edge Angle

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