A two-dimensional computational study on the fluid–structure interaction cause of wing pitch changes in dipteran flapping flight

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Specifically, the manoeuvres studied here were triggered by providing a sudden looming stimulus to a hovering moth, causing it to pitch up, fly backwards a short distance, and then pitch back Accepted 23 September 2011 SUMMARY Insects produce a variety of exquisitely controlled manoeuvres during natural flight behaviour. Here we show how hawkmoths produce and control one such manoeuvre, an avoidance response consisting of rapid pitching up, rearward flight, pitching down (often past the original pitch angle), and then pitching up slowly to equilibrium. We triggered these manoeuvres via a sudden visual stimulus in front of free-flying hawkmoths (Manduca sexta) while recording the animalsʼ body and wing movements via high-speed stereo videography. We then recreated the wing motions in a dynamically scaled model to: (1) associate wing kinematic changes with pitch torque production and (2)

Section: Dynamically Scaled Robotic Wing Experimentsmentioning

confidence: 99%

The mechanics and control of pitching manoeuvres in a freely flying hawkmoth (Manduca sexta)

Cheng

Deng

Hedrick

2011

164

135

“…They found that aerodynamic performance was enhanced when the wing was flapped at a 1/3 of the natural frequency. Ishihara et al studied passive pitching by modeling a rigid wing that was free to pitch and were able to generate sinusoidal motions that produced enough lift to support some Diptera (Ishihara et al, 2009). A number of other studies have explored the role of wing flexibility in avian flight (Heathcote et al, 2008;Kim et al, 2008) and thrust generation (Alben, 2008;Lauder et al, 2006;.…”

Section: Introductionmentioning

confidence: 99%

Flexible clap and fling in tiny insect flight

Miller

Peskin

2009

149

146

SUMMARYOf the insects that have been filmed in flight, those that are 1 mm in length or less often clap their wings together at the end of each upstroke and fling them apart at the beginning of each downstroke. This ʻclap and flingʼ motion is thought to augment the lift forces generated during flight. What has not been highlighted in previous work is that very large forces are required to clap the wings together and to fling the wings apart at the low Reynolds numbers relevant to these tiny insects. In this paper, we use the immersed boundary method to simulate clap and fling in rigid and flexible wings. We find that the drag forces generated during fling with rigid wings can be up to 10 times larger than what would be produced without the effects of wing-wing interaction. As the horizontal components of the forces generated during the end of the upstroke and beginning of the downstroke cancel as a result of the motion of the two wings, these forces cannot be used to generate thrust. As a result, clap and fling appears to be rather inefficient for the smallest flying insects. We also add flexibility to the wings and find that the maximum drag force generated during the fling can be reduced by about 50%. In some instances, the net lift forces generated are also improved relative to the rigid wing case. Supplementary material available online at

“…It has been suggested that the aerodynamic pressure is sufficient to produce the observed torsion using the static linear relation between the assumed aerodynamic pressure and the torsional stiffness of the wing (Ennos, 1988a). In our previous study (Ishihara et al, 2009), we used the flapping wing section model with a spring to model the wing torsional flexibility, and the finite element method to analyze the motion of the model wing interacting with the surrounding fluid. Under the dynamic similarity between the crane fly flight and our model flight, our model wing passively maintained a high angle of attack during the flapping translation and rotated quickly upon the stroke reversal without any prescribed pitching motion.…”

Section: Introductionmentioning

confidence: 99%

Passive maintenance of high angle of attack and its lift generation during flapping translation in crane fly wing

Ishihara

Yamashita

Horie

et al. 2009

Self Cite

SUMMARYWe have studied the passive maintenance of high angle of attack and its lift generation during the crane fly's flapping translation using a dynamically scaled model. Since the wing and the surrounding fluid interact with each other, the dynamic similarity between the model flight and actual insect flight was measured using not only the non-dimensional numbers for the fluid (the Reynolds and Strouhal numbers) but also those for the fluid-structure interaction (the mass and Cauchy numbers). A difference was observed between the mass number of the model and that of the actual insect because of the limitation of available solid materials. However, the dynamic similarity during the flapping translation was not much affected by the mass number since the inertial force during the flapping translation is not dominant because of the small acceleration. In our model flight, a high angle of attack of the wing was maintained passively during the flapping translation and the wing generated sufficient lift force to support the insect weight. The mechanism of the maintenance is the equilibrium between the elastic reaction force resulting from the wing torsion and the fluid dynamic pressure. Our model wing rotated quickly at the stroke reversal in spite of the reduced inertial effect of the wing mass compared with that of the actual insect. This result could be explained by the added mass from the surrounding fluid. Our results suggest that the pitching motion can be passive in the crane fly's flapping flight.