The added mass forces in insect flapping wings

Liu, Longgui; Sun, Mao

doi:10.1016/j.jtbi.2017.10.014

Cited by 21 publications

(12 citation statements)

References 24 publications

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“…Each of them satisfies the Laplace equation, and represents the velocity potential due to the body motion with unit velocity in the jth mode: j = 1, 2, 3 correspond to unit translational velocities in the x 1 , x 2 and x 3 directions (figure 8), respectively, and j = 4, 5, 6 correspond to unit rotational velocities about the x 1 , x 2 and x 3 axes (figure 8), respectively. The authors recently developed a code for solving the velocity potentials and computing the added-mass force (Liu & Sun 2018). The code was based on a three-dimension panel method.…”

Section: A2 Flow Solution Methods and Grid Testsmentioning

confidence: 99%

“…Our group recently developed a code for computing the added-mass force of flapping wings, using the three-dimensional panel method (Liu & Sun 2018); see appendix A for the validation of the code and convergence study of the panel method. Using the code we calculated the added-mass force of the mosquito wing and the results are shown in figure 9, compared with the results computed by solving the Navier-Stokes equations.…”

Section: Force Peak At the Beginning Of The Downstroke Or Upstrokementioning

confidence: 99%

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Aerodynamic-force production mechanisms in hovering mosquitoes

Liu

Sun

2020

J. Fluid Mech.

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Section: A2 Flow Solution Methods and Grid Testsmentioning

confidence: 99%

Section: Force Peak At the Beginning Of The Downstroke Or Upstrokementioning

confidence: 99%

Aerodynamic-force production mechanisms in hovering mosquitoes

Liu

Sun

2020

J. Fluid Mech.

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“…His results show that the added mass of a rigid body moving in an incompressible fluid can be computed by solving a separate potential flow. Our group recently developed a code for computing the added mass force of flapping wings (Liu and Sun 2018). Using the code we calculated the added mass force during the rowing period and the results are shown in Figure 12a and b.…”

Section: Aerodynamic-force Mechanismsmentioning

confidence: 99%

Very small insects use novel wing flapping and drag principle to generate the weight-supporting vertical force

Cheng

Sun

2018

J. Fluid Mech.

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The effect of air viscosity on the flow around an insect wing increases as insect size decreases. For the smallest insects (wing length R below 1 mm), the viscous effect is so large that lift-generation mechanisms used by their larger counterparts become ineffective. How the weight-supporting vertical force is generated is unknown. To elucidate the aerodynamic mechanisms responsible, we measure the wing kinematics of the tiny wasp Encarsia formosa (0.6 mm R) in hovering or very slow ascending flight and compute and analyze the aerodynamic forces. We find that the insects perform two unusual wing-motions. One is "rowing": the wings move fast downward and backward, like stroking oars; the other is the previously discovered Weis-Fogh 'fling'. The rowing produces 70% of the required vertical force and the Weis-Fogh 'fling' the other 30%. The oaring wing mainly produces an approximately up-pointing drag, resulting in the vertical force. Because each oaring produces a starting flow, the drag is unsteady in nature and much greater than that in steady motion at the same velocities and angles of attack. Furthermore, our computation shows that if the tiny wasps employed the usual wing kinematics of the larger insects (flapping back and forth in a horizontal plane), vertical force produced would be only 1/3 of that by the real wing kinematics; i.e. they must use the special wing movements to overcome the problem of large viscous effects encountered by the commonly used flapping kinematics. We for the first time observe very small insects using drag to support their weight and explain how a net vertical force is generated when the drag principle is applied.Although the wing of an insect beats at high frequency (usually above 100 Hz), the velocity of the wing relative the undisturbed air is small, owing to the small wing-length. As a result, the vertical force coefficient of the wing required to balance the weight is relatively high; the mean vertical force coefficient required is around 2

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“…Nevertheless, by resolving the body's acceleration relative to the inertial frame in body axes [28], it becomes possible to define an added mass tensor that depends only on the shape and size of the body. The added mass forces involved in insect flight are especially significant at stroke reversal [29], when the magnitude of the wing's acceleration is greatest, and when the wing's orientation is such that a significant part of its acceleration is directed normal to its chord. It is important to emphasize that the added mass force is simply an unsteady pressure force arising from acceleration of the fluid, and is not connected with any identifiable mass of fluid actually being carried along with the body.…”

Section: Form Of the Unsteady Forcesmentioning

confidence: 99%

A semi-empirical model of the aerodynamics of manoeuvring insect flight

Walker

Taylor

2021

J. R. Soc. Interface.

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Blade element modelling provides a quick analytical method for estimating the aerodynamic forces produced during insect flight, but such models have yet to be tested rigorously using kinematic data recorded from free-flying insects. This is largely because of the paucity of detailed free-flight kinematic data, but also because analytical limitations in existing blade element models mean that they cannot incorporate the complex three-dimensional movements of the wings and body that occur during insect flight. Here, we present a blade element model with empirically fitted aerodynamic force coefficients that incorporates the full three-dimensional wing kinematics of manoeuvring Eristalis hoverflies, including torsional deformation of their wings. The two free parameters were fitted to a large free-flight dataset comprising N = 26 541 wingbeats, and the fitted model captured approximately 80% of the variation in the stroke-averaged forces in the sagittal plane. We tested the robustness of the model by subsampling the data, and found little variation in the parameter estimates across subsamples comprising 10% of the flight sequences. The simplicity and generality of the model that we present is such that it can be readily applied to kinematic datasets from other insects, and also used for the study of insect flight dynamics.

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The added mass forces in insect flapping wings

Cited by 21 publications

References 24 publications

Aerodynamic-force production mechanisms in hovering mosquitoes

Aerodynamic-force production mechanisms in hovering mosquitoes

Very small insects use novel wing flapping and drag principle to generate the weight-supporting vertical force

A semi-empirical model of the aerodynamics of manoeuvring insect flight

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