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Centripetal Acceleration Reaction: An Effective and Robust Mechanism for Flapping Flight in Insects.

Zhang C, Hedrick TL, Mittal R - PLoS ONE (2015)

Bottom Line: Despite intense study by physicists and biologists, we do not fully understand the unsteady aerodynamics that relate insect wing morphology and kinematics to lift generation.Furthermore, unlike the lift due to vorticity, centripetal acceleration reaction lift is insensitive to Reynolds number and to environmental flow perturbations, making it an important contributor to insect flight stability and miniaturization.This force mechanism also has broad implications for flow-induced deformation and vibration, underwater locomotion and flows involving bubbles and droplets.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, the Johns Hopkins University, Baltimore, Maryland, United States of America.

ABSTRACT
Despite intense study by physicists and biologists, we do not fully understand the unsteady aerodynamics that relate insect wing morphology and kinematics to lift generation. Here, we formulate a force partitioning method (FPM) and implement it within a computational fluid dynamic model to provide an unambiguous and physically insightful division of aerodynamic force into components associated with wing kinematics, vorticity, and viscosity. Application of the FPM to hawkmoth and fruit fly flight shows that the leading-edge vortex is the dominant mechanism for lift generation for both these insects and contributes between 72-85% of the net lift. However, there is another, previously unidentified mechanism, the centripetal acceleration reaction, which generates up to 17% of the net lift. The centripetal acceleration reaction is similar to the classical inviscid added-mass in that it depends only on the kinematics (i.e. accelerations) of the body, but is different in that it requires the satisfaction of the no-slip condition, and a combination of tangential motion and rotation of the wing surface. Furthermore, the classical added-mass force is identically zero for cyclic motion but this is not true of the centripetal acceleration reaction. Furthermore, unlike the lift due to vorticity, centripetal acceleration reaction lift is insensitive to Reynolds number and to environmental flow perturbations, making it an important contributor to insect flight stability and miniaturization. This force mechanism also has broad implications for flow-induced deformation and vibration, underwater locomotion and flows involving bubbles and droplets.

No MeSH data available.


Related in: MedlinePlus

(a) Typical non-uniform Cartesian mesh employed in the simulations. (b) Schematic of the control volume (not to scale) employed for the simulations and FPM. (c) Kinematics of the wing of the hovering hawkmoth and (d) fruit fly. In these plots, the trajectory of the leading edge of the wings at 2/3 span is identified by a thick line which is blue during downstroke and pink during upstroke. The chordlines at 2/3 span are also identified by black lines with circular “heads”. Time series of three characteristic angles (see inset in (f)) that define the wing kinematics for the (e) hawkmoth and (f) the fruit fly. For the hawkmoth, the instantaneous 3D wing shape and kinematics were quantified via high-speed stereo videogrammetry from recordings of the animal hovering steadily in front of an artificial flower [9]. For the fruit fly, a flat-plate wing was constructed from a high-resolution image of a fruit fly wing. Flapping kinematics consisting of three angular degrees of freedom were then extracted via high-speed stereo videogrammetry of a fruit fly, hovering shortly after takeoff, and imposed on the wing, resulting in rigid wing flapping kinematics. Fruit fly wings exhibit little deformation and the use of rigid wing kinematics is typical of mechanical [10] and recent computational [11–13] models of their flight.
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pone.0132093.g001: (a) Typical non-uniform Cartesian mesh employed in the simulations. (b) Schematic of the control volume (not to scale) employed for the simulations and FPM. (c) Kinematics of the wing of the hovering hawkmoth and (d) fruit fly. In these plots, the trajectory of the leading edge of the wings at 2/3 span is identified by a thick line which is blue during downstroke and pink during upstroke. The chordlines at 2/3 span are also identified by black lines with circular “heads”. Time series of three characteristic angles (see inset in (f)) that define the wing kinematics for the (e) hawkmoth and (f) the fruit fly. For the hawkmoth, the instantaneous 3D wing shape and kinematics were quantified via high-speed stereo videogrammetry from recordings of the animal hovering steadily in front of an artificial flower [9]. For the fruit fly, a flat-plate wing was constructed from a high-resolution image of a fruit fly wing. Flapping kinematics consisting of three angular degrees of freedom were then extracted via high-speed stereo videogrammetry of a fruit fly, hovering shortly after takeoff, and imposed on the wing, resulting in rigid wing flapping kinematics. Fruit fly wings exhibit little deformation and the use of rigid wing kinematics is typical of mechanical [10] and recent computational [11–13] models of their flight.

Mentions: The formulation is applied to the flapping wings of a hovering hawkmoth (Manduca sexta) and a fruit fly (Drosophila melanogaster) in slow climbing flight to reveal similarities and differences in the mechanism of lift production in these insects. Besides the dissimilarities in wing kinematics and the shape and deformation characteristics of the wings (Fig 1), the two flyers operate in Reynolds number regimes separated by over an order of magnitude. A comparative analysis of these two cases therefore provides an excellent substrate for investigating the scaling of lift force.


Centripetal Acceleration Reaction: An Effective and Robust Mechanism for Flapping Flight in Insects.

Zhang C, Hedrick TL, Mittal R - PLoS ONE (2015)

(a) Typical non-uniform Cartesian mesh employed in the simulations. (b) Schematic of the control volume (not to scale) employed for the simulations and FPM. (c) Kinematics of the wing of the hovering hawkmoth and (d) fruit fly. In these plots, the trajectory of the leading edge of the wings at 2/3 span is identified by a thick line which is blue during downstroke and pink during upstroke. The chordlines at 2/3 span are also identified by black lines with circular “heads”. Time series of three characteristic angles (see inset in (f)) that define the wing kinematics for the (e) hawkmoth and (f) the fruit fly. For the hawkmoth, the instantaneous 3D wing shape and kinematics were quantified via high-speed stereo videogrammetry from recordings of the animal hovering steadily in front of an artificial flower [9]. For the fruit fly, a flat-plate wing was constructed from a high-resolution image of a fruit fly wing. Flapping kinematics consisting of three angular degrees of freedom were then extracted via high-speed stereo videogrammetry of a fruit fly, hovering shortly after takeoff, and imposed on the wing, resulting in rigid wing flapping kinematics. Fruit fly wings exhibit little deformation and the use of rigid wing kinematics is typical of mechanical [10] and recent computational [11–13] models of their flight.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4529139&req=5

pone.0132093.g001: (a) Typical non-uniform Cartesian mesh employed in the simulations. (b) Schematic of the control volume (not to scale) employed for the simulations and FPM. (c) Kinematics of the wing of the hovering hawkmoth and (d) fruit fly. In these plots, the trajectory of the leading edge of the wings at 2/3 span is identified by a thick line which is blue during downstroke and pink during upstroke. The chordlines at 2/3 span are also identified by black lines with circular “heads”. Time series of three characteristic angles (see inset in (f)) that define the wing kinematics for the (e) hawkmoth and (f) the fruit fly. For the hawkmoth, the instantaneous 3D wing shape and kinematics were quantified via high-speed stereo videogrammetry from recordings of the animal hovering steadily in front of an artificial flower [9]. For the fruit fly, a flat-plate wing was constructed from a high-resolution image of a fruit fly wing. Flapping kinematics consisting of three angular degrees of freedom were then extracted via high-speed stereo videogrammetry of a fruit fly, hovering shortly after takeoff, and imposed on the wing, resulting in rigid wing flapping kinematics. Fruit fly wings exhibit little deformation and the use of rigid wing kinematics is typical of mechanical [10] and recent computational [11–13] models of their flight.
Mentions: The formulation is applied to the flapping wings of a hovering hawkmoth (Manduca sexta) and a fruit fly (Drosophila melanogaster) in slow climbing flight to reveal similarities and differences in the mechanism of lift production in these insects. Besides the dissimilarities in wing kinematics and the shape and deformation characteristics of the wings (Fig 1), the two flyers operate in Reynolds number regimes separated by over an order of magnitude. A comparative analysis of these two cases therefore provides an excellent substrate for investigating the scaling of lift force.

Bottom Line: Despite intense study by physicists and biologists, we do not fully understand the unsteady aerodynamics that relate insect wing morphology and kinematics to lift generation.Furthermore, unlike the lift due to vorticity, centripetal acceleration reaction lift is insensitive to Reynolds number and to environmental flow perturbations, making it an important contributor to insect flight stability and miniaturization.This force mechanism also has broad implications for flow-induced deformation and vibration, underwater locomotion and flows involving bubbles and droplets.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, the Johns Hopkins University, Baltimore, Maryland, United States of America.

ABSTRACT
Despite intense study by physicists and biologists, we do not fully understand the unsteady aerodynamics that relate insect wing morphology and kinematics to lift generation. Here, we formulate a force partitioning method (FPM) and implement it within a computational fluid dynamic model to provide an unambiguous and physically insightful division of aerodynamic force into components associated with wing kinematics, vorticity, and viscosity. Application of the FPM to hawkmoth and fruit fly flight shows that the leading-edge vortex is the dominant mechanism for lift generation for both these insects and contributes between 72-85% of the net lift. However, there is another, previously unidentified mechanism, the centripetal acceleration reaction, which generates up to 17% of the net lift. The centripetal acceleration reaction is similar to the classical inviscid added-mass in that it depends only on the kinematics (i.e. accelerations) of the body, but is different in that it requires the satisfaction of the no-slip condition, and a combination of tangential motion and rotation of the wing surface. Furthermore, the classical added-mass force is identically zero for cyclic motion but this is not true of the centripetal acceleration reaction. Furthermore, unlike the lift due to vorticity, centripetal acceleration reaction lift is insensitive to Reynolds number and to environmental flow perturbations, making it an important contributor to insect flight stability and miniaturization. This force mechanism also has broad implications for flow-induced deformation and vibration, underwater locomotion and flows involving bubbles and droplets.

No MeSH data available.


Related in: MedlinePlus