6 results on '"Mao, Sun"'
Search Results
2. Generation of the pitch moment during the controlled flight after takeoff of fruitflies
- Author
-
Jiang Hao Wu, Mao Sun, and Mao Wei Chen
- Subjects
030110 physiology ,0301 basic medicine ,Kinematics ,Inertia ,Arthropoda ,Physiology ,Velocity ,lcsh:Medicine ,02 engineering and technology ,03 medical and health sciences ,Aerodynamics ,Motion ,020401 chemical engineering ,Wings ,Medicine and Health Sciences ,Torque ,Animals ,Takeoff ,0204 chemical engineering ,Animal Anatomy ,lcsh:Science ,Moment of Inertia ,Physics ,Multidisciplinary ,Wing ,Angle of attack ,Biological Locomotion ,lcsh:R ,Organisms ,Biology and Life Sciences ,Classical Mechanics ,Mechanics ,Moment of inertia ,Invertebrates ,Biomechanical Phenomena ,Dynamics ,Moment (mathematics) ,Aerodynamic force ,Insects ,Drosophila melanogaster ,Flight, Animal ,Physical Sciences ,lcsh:Q ,Pitching moment ,Insect Flight ,Zoology ,Flight (Biology) ,Research Article - Abstract
In the present paper, the controlled flight of fruitflies after voluntary takeoff is studied. Wing and body kinematics of the insects after takeoff are measured using high-speed video techniques, and the aerodynamic force and moment are calculated by the computational fluid dynamics method based on the measured data. How the control moments are generated is analyzed by correlating the computed moments with the wing kinematics. A fruit-fly has a large pitch-up angular velocity owing to the takeoff jump and the fly controls its body attitude by producing pitching moments. It is found that the pitching moment is produced by changes in both the aerodynamic force and the moment arm. The change in the aerodynamic force is mainly due to the change in angle of attack. The change in the moment arm is mainly due to the change in the mean stroke angle and deviation angle, and the deviation angle plays a more important role than the mean stroke angle in changing the moment arm (note that change in deviation angle implies variation in the position of the aerodynamic stroke plane with respect to the anatomical stroke plane). This is unlike the case of fruitflies correcting pitch perturbations in steady free flight, where they produce pitching moment mainly by changes in mean stroke angle.
- Published
- 2016
3. Effects of wing deformation on aerodynamic forces in hovering hovertlies.
- Author
-
Gang Du and Mao Sun
- Subjects
- *
WINGS (Anatomy) , *SYRPHIDAE , *NUMERICAL solutions to Navier-Stokes equations , *DRAG (Aerodynamics) , *LIFT (Aerodynamics) , *ANGLE of attack (Aerodynamics) , *BEHAVIOR - Abstract
We studied the effects of wing deformation on the aerodynamic forces of wings of hovering hoverflies by solving the Navier-Stokes equations on a dynamically deforming grid, employing the recently measured wing deformation data of hoverflies in free-flight. Three hoverf lies were considered. By taking out the camber deformation and the spanwise twist deformation one by one and by comparing the results of the deformable wing with those of the rigid flat-plate wing (the angle of attack of the rigid flatplate wing was equal to the local angle of attack at the radius of the second moment of wing area of the deformable wing), effects of camber deformation and spanwise twist were identified. The main results are as follows. For the hovering hoverf lies considered, the time courses of the lift, drag and aerodynamic power coefficients of the deformable wing are very similar to their counterparts of the rigid flat-plate wing, although lift of the deformable wing is about 10% larger, and its aerodynamic power required about 5% less than that of the rigid flat-plate wing. The difference in lift is mainly caused by the camber deformation, and the difference in power is mainly caused by the spanwise twist. The main reason that the deformation does not have a very large effect on the aerodynamic force is that, during hovering, the wing operates at a very high angle of attack (about 5odeg) and the flow is separated, and separated flow is not very sensitive to wing deformation. Thus, as a first approximation, the deformable wing in hover flight could be modeled by a rigid flat-plate wing with its angle of attack being equal to the local angle of attack at the radius of second moment of wing area of the deformable wing. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
4. Hovering of model insects: simulation by coupling equations of motion with Navier-Stokes equations.
- Author
-
Jiang Hao Wu, Yan Lai Zhang, and Mao Sun
- Subjects
INSECTS ,SPHINGIDAE ,FLIES ,OSCILLATIONS ,NAVIER-Stokes equations ,SIMULATION methods & models ,NUMERICAL analysis - Abstract
When an insect hovers, the centre of mass of its body oscillates around a point in the air and its body angle oscillates around a mean value, because of the periodically varying aerodynamic and inertial forces of the flapping wings. In the present paper, hover flight including body oscillations is simulated by coupling the equations of motion with the Navier-Stokes equations. The equations are solved numerically; periodical solutions representing the hover flight are obtained by the shooting method. Two model insects are considered, a dronefly and a hawkmoth; the former has relatively high wingbeat frequency (n) and small wing mass to body mass ratio, whilst the latter has relatively low wingbeat frequency and large wing mass to body mass ratio. The main results are as follows. (i) The body mainly has a horizontal oscillation; oscillation in the vertical direction is about 1/6 of that in the horizontal direction and oscillation in pitch angle is relatively small. (ii) For the hawkmoth, the peak-to-peak values of the horizontal velocity, displacement and pitch angle are 0.11 U (U is the mean velocity at the radius of gyration of the wing), 0.22=4mm (c is the mean chord length) and 4 deg., respectively. For the dronefly, the corresponding values are 0.02U, 0.05c=0.15mm and 0.3 deg., much smaller than those of the hawkmoth. (iii) The horizontal motion of the body decreases the relative velocity of the wings by a small amount. As a result, a larger angle of attack of the wing, and hence a larger drag to lift ratio or larger aerodynamic power, is required for hovering, compared with the case of neglecting body oscillations. For the hawkmoth, the angle of attack is about 3.5 deg. larger and the specific power about 9% larger than that in the case of neglecting the body oscillations; for the dronefly, the corresponding values are 0.7 deg. and 2%. (iv) The horizontal oscillation of the body consists of two parts; one (due to wing aerodynamic force) is proportional to 1/cn
2 and the other (due to wing inertial force) is proportional to wing mass to body mass ratio. For many insects, the values of 1/cn2 and wing mass to body mass ratio are much smaller than those of the hawkmoth, and the effects of body oscillation would be rather small; thus it is reasonable to neglect the body oscillations in studying their aerodynamics. [ABSTRACT FROM AUTHOR]- Published
- 2009
- Full Text
- View/download PDF
5. Aerodynamic Force Generation in Hovering Flight in a Tiny Insect.
- Author
-
Mao Sun and Xin Yu
- Subjects
- *
AERODYNAMICS , *REYNOLDS number , *SPEED , *INSECTS , *WINGS (Anatomy) , *NAVIER-Stokes equations - Abstract
Aerodynamic force generation in hovering flight in a tiny insect, Encarsia formosa, has been studied. The Reynolds number of the flapping wings (based on the mean chord length and the mean flapping velocity) is around 15. The flapping motion of the insect is unique in that the wing pair "claps" together near the end of an upstroke and "flings" open at the beginning of the subsequent downstroke. The method of solving the Navier-Stokes equations over moving overset grids is used. The fling produces a large lift peak at the beginning of the downstroke, the mechanism of which is the generation of a vortex ring containing a downward jet in a short period; the clap produces a large lift peak near the end of the subsequent upstroke by a similar mechanism. Because the vorticity generated during the clap and fling diffuses rapidly, the clap and fling has little influence on the flows in the rest part of the stroke cycle. The mean lift is enough to support the weight of the insect. The lift peaks due to the clap and fling result in more than 30% increase in mean lift coefficient compared to the case of flapping without clap and fling. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
6. Flapping-mode changes and aerodynamic mechanisms in miniature insects.
- Author
-
Yu Zhu Lyu, Hao Jie Zhu, and Mao Sun
- Subjects
- *
INSECTS , *REYNOLDS number , *AERODYNAMIC load - Abstract
Miniature insects fly at very low Reynolds number (Re); low Re means large viscous effect. If flapping as larger insects, sufficient vertical force cannot be produced. We measure the wing kinematics for miniature-insect species of different sizes and compute the aerodynamic forces. The planar upstroke commonly used by larger insects changes to a U-shaped upstroke, which becomes deeper as size or Re decreases. For relatively large miniature insects, the U-shaped upstroke produces a larger vertical force than a planar upstroke by having a larger wing velocity and, for very small ones, the deep U-shaped upstroke produces a large transient drag directed upwards, providing the required vertical force. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.