Characteristics of Dynamic Forces Generated by a Flapping Butterfly and its Wake Structure

2017 ◽  
Author(s):  
Masaki Fuchiwaki ◽  
Kazuhiro Tanaka
Keyword(s):  
Flow Field ◽  
Butterfly Wing ◽  
Vortex Loop ◽  
Insect Wing ◽  
Fluid Forces ◽  
Insect Wings ◽  
Piv Measurement ◽  
Dynamic Forces ◽  
Butterfly Wings ◽  
The Relationship

A typical example of the flow field around a moving elastic body is that around butterfly wings. Butterflies fly by skillfully controlling this flow field, and vortices are generated around their bodies. The motion of their elastic wings produces dynamic fluid forces by manipulating the flow field. For this reason, there has been increased academic interest in the flow field and dynamic fluid forces produced by butterfly wings. A number of recent studies have qualitatively and quantitatively examined the flow field around insect wings. In some such previous studies, the vortex ring or vortex loop formed on the wing was visualized. However, the characteristics of dynamic forces generated by the flapping insect wing are not yet sufficiently understood. The purpose of the present study is to investigate the characteristics of dynamic lift and thrust produced by the flapping butterfly wing and the relationship between the dynamic lift and thrust and the flow field around the butterfly. We conducted the dynamic lift and thrust measurements of a fixed flapping butterfly, Idea leuconoe, using a six-axes sensor. Moreover, two-dimensional PIV measurement was conducted in the wake of the butterfly. The butterfly produced dynamic lift in downward flapping which became maximum at a flapping angle of approximately 0.0 deg. At the same time, the butterfly produced negative dynamic thrust during downward flapping. The negative dynamic thrust was not produced hydrodynamically by a flapping butterfly wing because a jet was not formed in front of the butterfly. The negative dynamic thrust was the kicking force for jumping and the maximum of this kicking force was about 6.0 times as large as the weight. On the other hand, the butterfly produced dynamic thrust in upward flapping which was approximately 6.0 times as large as the weight of the butterfly. However, the attacking force by the abdomen of the butterfly was included in the dynamic thrust and we have not yet clarified quantitatively the dynamic thrust produced by the butterfly wing.

Dynamic Forces Acting on Elastic Heaving Airfoils Based on the Bending Stiffness Considerations

2014 ◽  
Author(s):  
Masaki Fuchiwaki ◽  
Tetsushi Nagata ◽  
Kazuhiro Tanaka
Keyword(s):  
Flow Field ◽  
Elastic Deformation ◽  
Vortex Flow ◽  
Moving Boundary ◽  
Bending Stiffness ◽  
Fluid Forces ◽  
Dynamic Forces ◽  
Flow Phenomena ◽  
The Impact ◽  
The Relationship

In recent years the flow field in the vicinity of moving airfoils capable of flexible elastic deformation has become a focus of attention, and its effects are beginning to be understood. Flow in the vicinity of an elastically deforming airfoil may be understood as a fluid-structure interaction (FSI) problem, and the motion and deformation of elastic airfoils, as well as the associated vortex flow phenomena in their vicinity, are complicated. Especially, the shape and hardness of the elastic regions of an airfoil may affect its rigidity and its bending characteristics and for this reason the influence of such airfoils on the flow fields around them require more detailed consideration. In this study, we fix the bending stiffness, which uniquely determines the nature of the elastic deformation of an elastic airfoil, and study the impact of changes in this quantity on the flow field, as well as the parameters that govern the fluid forces acting on the airfoil. In particular, our goal is to clarify the relationship between three key parameters, Strouhal number St, Reynolds number Re and bending stiffness K and is to elucidate the nature of the dynamic forces acting on an elastic airfoil as a function of these three dimensionless parameters. The bending stiffness K of the elastic airfoil is an important parameter that determines the bending characteristics and the moving boundary conditions at the wall surfaces in the fluid. By defining the new quantity St2/K, we showed that the characteristic of dynamic forces depends on the ratio St2/K.

Characteristics of Dynamic Forces Generated by a Flapping Butterfly

2013 ◽  
Author(s):  
Taichi Kuroki ◽  
Masaki Fuchiwaki ◽  
Kazuhiro Tanaka ◽  
Takahide Tabata
Keyword(s):  
Flow Field ◽  
Vortex Ring ◽  
Elastic Deformation ◽  
Micro Air Vehicles ◽  
Flapping Wing ◽  
Flapping Motion ◽  
Insect Wings ◽  
Dynamic Forces ◽  
The Relationship ◽  
Significant Attention

Many studies on the mechanism of butterfly flight have been carried out. A number of recent studies have examined the flow field around insect wings. Moreover, Micro-air-vehicles and micro-flight robots that mimic the flight mechanisms of insects have attracted significant attention, and a number of MAVs and micro-flight robots that use various devices have been reported. 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. The present authors developed a flapping-wing robot without tail wings and focused on the flow field around the wings created by the flapping motion and its elastic deformation. In the present study, we attempt to clarify the relationship between the vortex ring over the wing and the dynamic lift generated by the flapping wing. The dynamic lift becomes large rapidly in the downward flapping and reaches a maximum at a flapping angle of −30 deg. After the maximum, the dynamic lift decreases gradually and the dynamic lift in upward flapping is approximately constant. The growth of the vortex ring formed by the flapping wing was clarified to contribute significantly to the dynamic lift acting on the butterfly. We should consider the interaction of both vortex ring both in downward flapping and in upward flapping in order to estimate the dynamic lift exactly using the circulation of the vortex ring.

Dynamic Behaviors of Vortex Ring Rolled Up by a Butterfly Wing and its Dynamic Lift

2016 ◽  
Author(s):  
Masaki Fuchiwaki ◽  
Kazuhiro Tanaka
Keyword(s):  
Flow Field ◽  
Vortex Ring ◽  
Force Measurement ◽  
Three Dimensional ◽  
Vortex Structures ◽  
Dynamic Force ◽  
Butterfly Wing ◽  
Dynamic Behaviors ◽  
Insect Wings ◽  
Piv Measurement

The wing motion of a flying insect such as a butterfly produces fluid force by manipulating the flow field around the wing. These forces enable a butterfly to rapidly accelerate, turn, and hover. A number of recent studies have examined the flow field around insect wings. In recent years, quantitative flow visualization techniques, such as PIV measurement, have been advanced rapidly, and the study of the flow field around insect wings using PIV has been actively performed. As a result, the two- and three-dimensional vortex structures and their dynamic behaviors have been investigated quantitatively. However, the dynamic behaviors of these vortex structures have not been related to the dynamic force characteristics. The purpose of the present study is to clarify the relationship between the dynamic lift generated by the flapping butterfly wing and the dynamic behavior of the vortex ring rolled up from the butterfly wing as well as to investigate the role of the vortex ring. We conducted a dynamic force measurement of a flapping Cynthia cardui using a six-axes sensor and three kinds of shafts: a straight shaft, a short L-shaped shaft, and a long L-shaped shaft. Moreover, a two-dimensional PIV measurement was conducted in the wake of the butterfly. The butterfly is given not only negative dynamic lift but also the reactive force (positive lift) due to the jet flow induced by the vortex ring in the upward flapping. As a result, the butterfly produces dynamic lift in the downward flapping and produces not only negative dynamic lift but also dynamic lift in the upward flapping. Based on these results, it is considered that the vortex ring released into the wake contributes to the dynamic lift generated furing flight. That is, it was concluded that the vortex ring rolled up from the flapping wing has an important role in flight even after being released into the wake.

Numerical Simulation and Experimental Study of Inner Flow Field in Marine Centrifugal Pump

2014 ◽  
Vol 513-517 ◽  
pp. 4593-4596
Author(s):  
Xin Xiang Chen ◽  
Guo You Wang ◽  
Kai Wang ◽  
Ming Gao Tan ◽  
Liang Dong
Keyword(s):  
Flow Field ◽  
Centrifugal Pump ◽  
Particle Image ◽  
Practical Application ◽  
Total Head ◽  
Piv Measurement ◽  
Image Velocimetry ◽  
Calculation Results ◽  
Shaft Power ◽  
The Relationship

It was simulated the flow fields of the CLH-type marine centrifugal pump based on average N-S equations and standard k-ε turbulent model, using the ANSYS CFX12.1 code. With the calculation results, the velocity distribution of the flow field in the centrifugal pump is analyzed under different working conditions. The analogue results, which indicate the relationship between the total head, efficiency, shaft power and flow rate, are compared with performance experimental ones, and it shows that the simulation data coincides with experimental ones in allowable acceptance, which meet the requirements of practical application. Furthermore, in order to analyze the inner flow field distribution in the centrifugal pump in detail, and validate the simulation results, the inner flow field is tested by particle image velocimetry (PIV) measurement.

scholarly journals Numerical and Experimental Analyses of Three- Dimensional Unsteady Flow around a Micro-Pillar Subjected to Rotational Vibration

Micromachines ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 668 ◽  
Author(s):  
Kanji Kaneko ◽  
Takayuki Osawa ◽  
Yukinori Kametani ◽  
Takeshi Hayakawa ◽  
Yosuke Hasegawa ◽  
...  
Keyword(s):  
Flow Field ◽  
Moving Boundary ◽  
Three Dimensional ◽  
Steady Streaming ◽  
Micro Piv ◽  
Piv Measurement ◽  
Image Velocimetry ◽  
Measurement Tools ◽  
Rotational Vibration ◽  
Induced Flow

The steady streaming (SS) phenomenon is gaining increased attention in the microfluidics community, because it can generate net mass flow from zero-mean vibration. We developed numerical simulation and experimental measurement tools to analyze this vibration-induced flow, which has been challenging due to its unsteady nature. The validity of these analysis methods is confirmed by comparing the three-dimensional (3D) flow field and the resulting particle trajectories induced around a cylindrical micro-pillar under circular vibration. In the numerical modeling, we directly solved the flow in the Lagrangian frame so that the substrate with a micro-pillar becomes stationary, and the results were converted to a stationary Eulerian frame to compare with the experimental results. The present approach enables us to avoid the introduction of a moving boundary or infinitesimal perturbation approximation. The flow field obtained by the micron-resolution particle image velocimetry (micro-PIV) measurement supported the three-dimensionality observed in the numerical results, which could be important for controlling the mass transport and manipulating particulate objects in microfluidic systems.

scholarly journals A simple developmental model recapitulates complex insect wing venation patterns

2018 ◽  
Vol 115 (40) ◽  
pp. 9905-9910 ◽  
Author(s):  
Jordan Hoffmann ◽  
Seth Donoughe ◽  
Kathy Li ◽  
Mary K. Salcedo ◽  
Chris H. Rycroft
Keyword(s):  
Large Scale ◽  
Developmental Model ◽  
Wing Venation ◽  
Secondary Vein ◽  
Insect Wing ◽  
Geometric Patterns ◽  
Insect Wings ◽  
Left And Right ◽  
Vein Patterning ◽  
Geometric Arrangements

Insect wings are typically supported by thickened struts called veins. These veins form diverse geometric patterns across insects. For many insect species, even the left and right wings from the same individual have veins with unique topological arrangements, and little is known about how these patterns form. We present a large-scale quantitative study of the fingerprint-like “secondary veins.” We compile a dataset of wings from 232 species and 17 families from the order Odonata (dragonflies and damselflies), a group with particularly elaborate vein patterns. We characterize the geometric arrangements of veins and develop a simple model of secondary vein patterning. We show that our model is capable of recapitulating the vein geometries of species from other, distantly related winged insect clades.

scholarly journals Butterfly-wing pollination in Scadoxus and other South African Amaryllidaceae

2020 ◽  
Vol 193 (3) ◽  
pp. 363-374 ◽  
Author(s):  
Hannah C Butler ◽  
Steven D Johnson
Keyword(s):  
South African ◽  
Ventral Surface ◽  
Butterfly Wing ◽  
Pollen Transfer ◽  
Floral Structure ◽  
Pollination Mechanisms ◽  
Butterfly Wings ◽  
Floral Diversification ◽  
Swallowtail Butterflies ◽  
Transfer Mechanisms

Abstract Understanding the evolution of floral morphology requires information about the identity of pollinators as well as the specific mechanisms of pollen transfer. Based on preliminary field observations and floral structure, we hypothesized that pollination mechanisms involving the transfer of pollen on butterfly wings occur in several lineages of South African Amaryllidaceae. Here we report findings from a detailed study of butterfly-wing pollination in two subspecies of Scadoxus multiflorus and review the prevalence of this pollination mechanism among other Amaryllidaceae in southern Africa. We established that S. multiflorus subsp. katherinae is genetically self-incompatible and thus entirely reliant on pollinators for seed production. We determined that this subspecies is pollinated almost exclusively by large swallowtail butterflies, principally males of the mocker swallowtail Papilio dardanus cenea. Flowers of S. multiflorus subsp. multiflorus are pollinated by pierid and swallowtail butterflies. Pollen is deposited on the ventral surface of the wings of butterflies as they flutter over the strongly exserted stamens. We predict that butterfly-wing pollination occurs in at least nine species of South African Amaryllidaceae, which may reflect several independent origins of this mechanism. The flowers of these species are red or orange with strong herkogamy and are either bowl-brush or open-brush in shape. We provide maps of the distribution of pollen on the ventral surface of the wings of pollinators for four of these species. All four appear to be pollinated via the ventral surface of large butterfly wings, with the floral structure facilitating the process. These findings illustrate the importance of investigating pollen transfer mechanisms in order to understand patterns of floral diversification and floral convergence.

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