Vortex Structure of a Vortex Ring Over a Butterfly Wing and its Dynamic Behavior

2011 ◽  
Author(s):  
Masaki Fuchiwaki ◽  
Taichi Kuroki ◽  
Kazuhiro Tanaka ◽  
Takahide Tabata
Keyword(s):  
Dynamic Behavior ◽  
Vortex Ring ◽  
Large Scale ◽  
Leading Edge ◽  
Micro Air Vehicles ◽  
Butterfly Wing ◽  
Trailing Edge ◽  
Piv Measurement ◽  
Large Scale Vortex ◽  
Secondary Disasters

Micro-Air-Vehicles (MAVs) that mimic the flight mechanisms of insects have been attracting significant attention in recent years. These technologies are developed with the aim of lifesavings in the area with the risk of secondary disasters, maintenance works for constructions such as bridges, information collection on planet searches, monitoring of security risks for the purpose of security means. A number of researchers have attempted to develop small flap flying objects and MAV with various actuators and devices. However, these robots were not practical. One of the reasons for this is that the flying mechanism of insects has not yet been clarified sufficiently. We have clarified that a couple of large-scale vortex is formed over the wing. The purpose of the present study is to clarify the dynamic behavior and the detailed structure of the vortices of the flapping butterfly wing, and we carried out the PIV measurement around the flapping butterfly wing. The vortex ring develops over the wings when the wings flap downward to the bottom dead position and then passes through the butterfly completely and grows until reaching the wake at the bottom dead position. The vortex ring develops over the wing while growing from the leading edge toward the trailing edge. The maximum vorticity of the vortex ring over the wing moves from the leading edge to the trailing edge with the downward flapping. On the other hand, the vorticity of the LEV decays with downward flapping.

Three-Dimensional Vortex Structure Around a Free Flight Butterfly

2014 ◽  
Author(s):  
Masaki Fuchiwaki ◽  
Taichi Kuroki ◽  
Kazuhiro Tanaka ◽  
Takahide Tabata
Keyword(s):  
Flow Field ◽  
Dynamic Behavior ◽  
Vortex Ring ◽  
Vortex Structure ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Micro Air Vehicles ◽  
Free Flight ◽  
Single Vortex ◽  
Piv Measurement

Micro-air-vehicles (MAVs) and micro-flight robots that mimic the flight mechanisms of insects have attracted significant attention. From this reason, the flight mechanism of the butterflies and their flow fields also has attracted attention. A number of studies on the mechanism of butterfly flight have been carried out. Moreover, a number of recent studies have examined the flow field around insect wings. The present authors conducted a particle image velocimetry (PIV) measurement around the flapping wings of Cynthia cardui and Idea leuconoe and investigated the vortex structure and dynamic behavior produced. However, these results are for a flow field under a fixed condition. The vortex flow structure and the dynamic behavior generated by the wings of a butterfly in free flight are expected to be important for generating the aerodynamic forces required for flight. In the present study, we attempt to clarify the three-dimensional vortex structure around a butterfly in free flight by a scanning PIV measurement. The vortex ring formed by the front wings during the flapping downward grows without attenuation toward the wake. Moreover, during the flapping upward of the wings, a vortex rolls up from the wing, eventually forming a single vortex ring. This vortex ring forms in the vertical direction in contrast to vortex ring formed during the flapping downward, and we may anticipate that the two vortex rings interfere with each other as they advance toward the wake.

Dynamic behavior of diffusion flame interacting with a large-scale vortex by laser imaging techniques

2005 ◽  
Vol 30 (1) ◽  
pp. 465-473 ◽  
Author(s):  
Masaharu Komiyama ◽  
Tomoya Fujimura ◽  
Toshimi Takagi ◽  
Shinichi Kinoshita
Keyword(s):  
Dynamic Behavior ◽  
Diffusion Flame ◽  
Large Scale ◽  
Imaging Techniques ◽  
Laser Imaging ◽  
Large Scale Vortex

A Turbulent Boundary Layer Flow Over an Open Shallow Cavity

2016 ◽  
Author(s):  
Khaled J. Hammad
Keyword(s):  
Boundary Layer ◽  
Large Scale ◽  
Vector Fields ◽  
Turbulence Models ◽  
Leading Edge ◽  
Field Measurements ◽  
Recirculation Region ◽  
Mean Flow ◽  
Trailing Edge ◽  
Cavity Depth

Particle Image Velocimetry (PIV) was used to study the flow structure and turbulence, upstream, over, and downstream a shallow open cavity. Three sets of PIV measurements, corresponding to a turbulent incoming boundary layer and a cavity length-to-depth ratio of four, are reported. The cavity depth based Reynolds numbers were 21,000; 42,000; and 54,000. The selected flow configuration and well characterized inflow conditions allow for straightforward assessment of turbulence models and numerical schemes. All mean flow field measurements display a large flow recirculation region, spanning most of the cavity and a smaller, counter-rotating, secondary vortex, immediately downstream of the cavity leading edge. The Galilean decomposed instantaneous velocity vector fields, clearly demonstrate two distinct modes of interaction between the free shear and the cavity trailing edge. The first corresponds to a cascade of vortical structures emanating from the tip of the leading edge of the cavity that grow in size as they travel downstream and directly interact with the trailing edge, i.e., impinging vortices. The second represents vortices that travel above the trailing edge of the cavity, i.e., non-impinging vortices. In the case of impinging vortices, a strong, large scale region of recirculation forms inside the cavity and carries the flow disturbances, arising from the impingement of vortices on the trailing edge of the cavity, upstream in a manner that interacts with and influences the flow as it separates from the cavity leading edge.

Dynamic Behavior of a Vortex Ring over a Butterfly Wing and Its Dynamic Lift

2012 ◽  
Author(s):  
Taichi Kuroki ◽  
Masaki Fuchiwaki ◽  
Kazuhiro Tanaka ◽  
Takahide Tabata
Keyword(s):  
Dynamic Behavior ◽  
Vortex Ring ◽  
Butterfly Wing

Effect of the wing trailing-edge flaps and spoilers position on the jet-vortex wake behind an aircraft during takeoff and landing run

2019 ◽  
pp. 095441001988215
Author(s):  
Yu M Tsirkunov ◽  
MA Lobanova ◽  
AI Tsvetkov ◽  
BA Schepanyuk
Keyword(s):  
Large Scale ◽  
Stokes Equations ◽  
Computational Simulation ◽  
Leading Edge ◽  
Velocity Profiles ◽  
Essential Elements ◽  
Trailing Edge ◽  
Structure Of Flow ◽  
Trailing Edge Flaps ◽  
Calculated Velocity

The large-scale vortex structure of flow in the near wake behind an aircraft during its run on a runway is investigated numerically. The geometrical aircraft configuration was taken close to a mid-range commercial aircraft like Boeing 737-300. It included all essential elements: a body (fuselage), wings with winglets, horizontal and vertical stabilizers, engine nacelles, nacelle pylons, inboard flap track fairings, leading-edge and trailing-edge flaps, and spoilers. The position of flaps and spoilers corresponded to the takeoff and landing run conditions. Computational simulation was based on solving the Reynolds averaged Navier–Stokes equations closed with the Menter Shear Stress Transport turbulence model. Patterns of streamlines, fields of the axial vorticity and the turbulent intensity, vertical and horizontal velocity profiles in the wake are compared and discussed for both run regimes. The flow model was preliminary tested for validity by comparison of the calculated velocity profiles behind a reduced-scale aircraft model with those obtained in special wind tunnel experiments.

Flow structure on a simultaneously pitching and rotating wing

2014 ◽  
Vol 756 ◽  
pp. 354-383 ◽  
Author(s):  
M. Bross ◽  
D. Rockwell
Keyword(s):  
Flow Structure ◽  
Large Scale ◽  
Three Dimensional ◽  
Leading Edge ◽  
Tip Vortex ◽  
Pure Rotation ◽  
Large Scale Vortex ◽  
Edge Vortex ◽  
Vorticity Flux ◽  
Rotating Wing

AbstractA technique of particle image velocimetry is employed to characterize the three-dimensional flow structure on a wing subjected to simultaneous pitch-up and rotational motions. Distinctive vortical structures arise, relative to the well-known patterns on a wing undergoing either pure pitch-up or pure rotation. The features associated with these simultaneous motions include: stabilization of the large-scale vortex generated at the leading edge, which, for pure pitch-up motion, rapidly departs from the leading-edge region; preservation of the coherent vortex system involving both the tip vortex and the leading-edge vortex (LEV), which is severely degraded for pure rotational motion; and rapid relaxation of the flow structure upon termination of the pitch-up component, whereby the relaxed flow converges to a similar state irrespective of the pitch rate. Three-dimensional surfaces of iso-$\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}{Q}$and helicity are employed in conjunction with sectional representations of spanwise vorticity, velocity and vorticity flux to interpret the flow physics.

scholarly journals Altimetric observations of surface characteristics of the Antarctic ice sheet

1997 ◽  
Vol 43 (144) ◽  
pp. 265-275 ◽  
Author(s):  
Benoît Legrésy ◽  
Frédérique Rémy
Keyword(s):  
Large Scale ◽  
Ice Sheet ◽  
Leading Edge ◽  
Small Scale ◽  
Height Measurement ◽  
Trailing Edge ◽  
Antarctic Ice Sheet ◽  
Linear Effect ◽  
Continental Scale ◽  
The Antarctic

AbstractThe aim of this paper is to investigate the geophysical characteristics of the Antarctic ice sheet using radar altimetric observations. To do this, we use an altimetric waveform simulator, in situ observations, ERS-1 (European remote-sensing satellite) data and SPOT (Satellite pour l’observation de la terre) images. The small-scale study takes place at Dome C, Terre Adélie, which is a relatively flat region with gentle undulations and low wind speed. Despite this, the altimetric waveform parameters (height, energy, leading edge and trailing edge) are highly noisy. The effect of undulations on the waveform parameters is found to be dominant. The combination of a subsurface signal and a rough surface produces a linear effect on the altimetric backscattering or on the trailing edge of the waveform, but a strongly non-linear effect on the leading edge of the waveform or height estimation. As a consequence, the height measurement is very sensitive to the altimeter technical or orbital characteristics and is not reproducible from one mission to another. Observations show sastrugi fields that enhance the leading edge and affect the whole waveform. Observed local backscattering changes, probably due to local variations in surface microroughness, enhance the backscattered energy and may artificially create a topographic signal. The continental-scale study shows coherent patterns. Even if both surface and subsurface components affect the altimetric observation, the large-scale signal is mostly controlled by surface backscattering variations. The surface or near-subsurface characteristics of the snowpack may then be reached by altimetric observations.

scholarly journals Dynamic behavior of the vortex ring formed on a butterfly wing

2013 ◽  
Vol 54 (1) ◽  
Author(s):  
Masaki Fuchiwaki ◽  
Taichi Kuroki ◽  
Kazuhiro Tanaka ◽  
Takahide Tababa
Keyword(s):  
Dynamic Behavior ◽  
Vortex Ring ◽  
Butterfly Wing

scholarly journals Altimetric observations of surface characteristics of the Antarctic ice sheet

1997 ◽  
Vol 43 (144) ◽  
pp. 265-275 ◽  
Author(s):  
Benoît Legrésy ◽  
Frédérique Rémy
Keyword(s):  
Large Scale ◽  
Ice Sheet ◽  
Leading Edge ◽  
Small Scale ◽  
Height Measurement ◽  
Trailing Edge ◽  
Antarctic Ice Sheet ◽  
Linear Effect ◽  
Continental Scale ◽  
The Antarctic

AbstractThe aim of this paper is to investigate the geophysical characteristics of the Antarctic ice sheet using radar altimetric observations. To do this, we use an altimetric waveform simulator, in situ observations, ERS-1 (European remote-sensing satellite) data and SPOT (Satellite pour l’observation de la terre) images. The small-scale study takes place at Dome C, Terre Adélie, which is a relatively flat region with gentle undulations and low wind speed. Despite this, the altimetric waveform parameters (height, energy, leading edge and trailing edge) are highly noisy. The effect of undulations on the waveform parameters is found to be dominant. The combination of a subsurface signal and a rough surface produces a linear effect on the altimetric backscattering or on the trailing edge of the waveform, but a strongly non-linear effect on the leading edge of the waveform or height estimation. As a consequence, the height measurement is very sensitive to the altimeter technical or orbital characteristics and is not reproducible from one mission to another. Observations show sastrugi fields that enhance the leading edge and affect the whole waveform. Observed local backscattering changes, probably due to local variations in surface microroughness, enhance the backscattered energy and may artificially create a topographic signal. The continental-scale study shows coherent patterns. Even if both surface and subsurface components affect the altimetric observation, the large-scale signal is mostly controlled by surface backscattering variations. The surface or near-subsurface characteristics of the snowpack may then be reached by altimetric observations.

scholarly journals Optimization of Flapping Airfoils for Maximum Thrust and Propulsive Efficiency

10.14311/508 ◽  
2004 ◽  
Vol 44 (1) ◽  
Author(s):  
I. H. Tuncer ◽  
M. Kay
Keyword(s):  
Large Scale ◽  
High Efficiency ◽  
Leading Edge ◽  
Laminar Flows ◽  
Navier Stokes ◽  
Propulsive Efficiency ◽  
Thrust Generation ◽  
Optimization Function ◽  
Optimization Parameters ◽  
Large Scale Vortex

A numerical optimization algorithm based on the steepest decent along the variation of the optimization function is implemented for maximizing the thrust and/or propulsive efficiency of a single flapping airfoil. Unsteady, low speed laminar flows are computed using a Navier-Stokes solver on moving overset grids. The flapping motion of the airfoil is described by a combined sinusoidal plunge and pitching motion. Optimization parameters are taken to be the amplitudes of the plunge and pitching motions, and the phase shift between them. Computations are performed in parallel in a work station cluster. The numerical simulations show that high thrust values may be obtained at the expense of reduced efficiency. For high efficiency in thrust generation, the induced angle of attack of the airfoil is reduced and large scale vortex formations at the leading edge are prevented. 

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