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Article type: Cover
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Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Article type: Appendix
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Article type: Appendix
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Article type: Index
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A1-A7
Published: August 02, 2008
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Masayuki NAKAJIMA, Hiroyuki FURUKAWA
Article type: Article
Session ID: 601
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In a study of a flow caused by a rotating disk in a casing, as for many of past studies, most of the form of a rotating disk is not considered. However, it became clear by a study of late years that a gap of a radius direction affected a flow between a casing base and rotating disks greatly. In this study, we used 7 different rotating disks and changed size of a gap in a cylinder casing and tested it about the influence that a radius direction gap gave to a flow near the fixed disk. As a result, it has been observed that "bead-like vortex" is generated in one of seven disks. "Bead-like vortex" is investigated in detail and the result of the experiment is shown in this paper.
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Yutaka CHIYOMORI, Takashi WATANABE, Hiroyuki FURUKAWA
Article type: Article
Session ID: 602
Published: August 02, 2008
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The purpose of this study is to analyze which visualization methods are the best for the flow around a rotating disc in a cylindrical enclosure. We use the methods based on Q value, pressure hessian and singular point and compare the physical experiment visualization with the numerical results. The spiral can be visualized clearly and vortex structures are extracted by the pressure hessian method.
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Hui Ji, Takao Suzuki, Akira Sanse, Fujio Yamamoto
Article type: Article
Session ID: 603
Published: August 02, 2008
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We introduce hybrid unsteady-flow simulation combining Particle Tracking Velocimetry (PTV) and Direct Numerical Simulation (DNS), and investigate planar jet flows at low Reynolds numbers (Re = 500 and 2000, based on the nozzle height). By comparing these results with the original PTV velocity fields and the results of two-dimensional DNS, we demonstrate the capabilities of the hybrid simulation.
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Takashi Misaka, Shigeru Obayashi, Izumi Yamada, Yoshinori Okuno
Article type: Article
Session ID: 604
Published: August 02, 2008
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Numerical simulation of aircraft's wake turbulence was carried out by integrating lidar measurements. Four-dimensional variational method (4D-Var) was applied to integrate the lidar measurements into three-dimensional large eddy simulation (LES). This paper describes the results using lidar measurements at Sendai airport.
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Kazuyuki UENO, Yuko MATSUMOTO
Article type: Article
Session ID: 605
Published: August 02, 2008
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Decomposition of incompressible flow fields into dipole flows with various length scales are proposed by using a continuous wavelet transform. Outline of decomposition is explained and examples of dipole decomposition are shown in this study. Dipole decomposition will give new physical insight into multi-scale dynamics of incompressible flows.
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Susumu SHIRAYAMA, Akira EGAWA
Article type: Article
Session ID: 606
Published: August 02, 2008
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As complexity of computational/experimental raw data in fluid dynamics increases, interpretation of visualized results becomes more difficult. And then, interpretation of the results by experts is of necessity required. It is important to know where their attentions are focused. In this paper, we propose a new method of segmentation based on visual attention of visualized information.
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Yuriko TAKESHIMA, Issei FUJISHIRO
Article type: Article
Session ID: 607
Published: August 02, 2008
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Modular Visualization Environments (MVEs) have been commonly used in many disciplines including fluid science. However, it is still difficult for scientists and engineers, who are not always visualization experts, to make full use of many built-in modules by taking into account their usability and interdependency for constructing optimal visualization workflows. In this report, we present a fundamental design of flow visualization ontology, which gives the basis for a cooperative MVE, called VIDELICET (Vlsualization DEsign and Llfe CyclE managemenT), to suggest best initial workflow candidates to the users.
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Issei FUJISHIRO, Yuriko TAKESHIMA, Ryota NARAOKA, Shigeo TAKAHASHI
Article type: Article
Session ID: 608
Published: August 02, 2008
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In our previous study, we have built on differential topology to come up with a framework to optimally locate a single parallel right source for shading a snapshot volume by ray-casting. This article is an initial report which attempts to extend the framework to time-varying volumes. By deploying a sophisticated scheme to search for an optimal trajectory of a moving light source, the extended framework can produce volume rendered animations whose enriched 3D cues facilitate a viewer tracking feature behavior embedded in the dynamical volume. A preliminary experiment with a 4D analytic volume was performed to evaluate the effectiveness of the extended framework.
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Toshio NAKAYAMA, Makoto OHTA, Daniel A. RUFENACHT, Akira TAKAHASHI
Article type: Article
Session ID: 701
Published: August 02, 2008
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In this research, we report the effect of each stent strut in aneurysm neck on hemodynamics using the computational fluid dynamics (CFD). The stent strut that deleted a part of it was constructed and that stent was stenting in aneurysm neck, CFD was performed using its shape. By comparing the results of removal stent strut case, the normal stenting case, and the no stenting case, the effect on hemodynamics by each stent strut was researched. From the results, we showed the wall shear stress distribution's greatly changing.
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Shimpei KOHRI, Tsutomu TAJIKAWA, Kenkichi Ohba
Article type: Article
Session ID: 702
Published: August 02, 2008
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For measurement of local blood velocity, a less-invasive miniaturized fiber-optic LDV (laser Doppler velocimetry) sensor was developed as a monitoring device for clinical use. By the method of a chemical etching, a convex lens-like surface was formed on the fiber tip. Laser emitted from the tip was focused and formed measuring volume, which enabled us to measure the velocity of steady blood flow in previous study. In order to measure local velocity of pulsatile blood flow, the optical system and the best curvature radius of the sensor tip were newly designed. By the present fiber-optic LDV sensor, local velocity and its profile in the flow duct were successfully measured in pulsatile flow of a dense suspension with the same optical property as blood, which proved the capability of the sensor as a diagnostic device.
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Yuuki NAKAMURA, Masao WATANABE, Masaki IRIBE, Mizuho MATSUBARA
Article type: Article
Session ID: 703
Published: August 02, 2008
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Nailfold video capillaroscopy (NVC) can observe the micro vascular structure non-invasively. We developed NVC by using high speed digital video camera to evaluate both micro vascular structure and red blood cell movement quantitatively The objects of this study are to evaluate the radius distribution of micro vascular by level-set method and also the red blood cell velocity by tracing plasma gap between blood cells.
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Hiroyuki MIKI, Shingo KODAIRA, Yun LUO, Masaru HIGA, Toshiyuki TAKAGI
Article type: Article
Session ID: 704
Published: August 02, 2008
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Less invasive hemostatic clamp is proposed and made experimentally. Clamping mechanism of this instrument is based on the conventional one, and utilizes superelastic behavior of an shape memory alloy wire. First, its clamping property was estimated experimentally without any animal experiments, considering whether the deformation property of an SMA wire affects clamping property. From these experiments, it was found that this newly occlusive instrument had less invasiveness compared with conventional ones.
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Koki TAKIURA, Shuichi MOCHIZUKI
Article type: Article
Session ID: 705
Published: August 02, 2008
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The real-time spatiotemporal analysis of thrombus formation is still difficult in blood pumps. Platelets are activated by blood flow and pump materials. Activated platelets release ADP, ATP, serotonin, etc. ATP can be detected using a luciferin-luciferase (L-L) reagent with high sensitivity. A L-L reagent reacts with ATP to emit light, then it can be detected with a photomultiplier tube (PMT) and a CCD camera, and this would realize the detailed analysis of platelet activation and also the thrombus formation in blood pumps. As a preliminary study, the blood clotting in the test tube was observed using a L-L reagent with a PMT and an electron multiplying CCD camera.
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Norikazu ISHIMATSU, Masaaki TAMAGAWA
Article type: Article
Session ID: 706
Published: August 02, 2008
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All the region of circulatory system can not be analyzed using computational fluid dynamics (CFD), because the structure is so complicated and the analysis region is restricted by computer memory. In order to analyze the flows, it is necessary to simplify and investigate the complicated network structure of vascular system quantitatively. We showed quantification of complicated structure using fractal dimension in our previous studies. This paper describes the relation between the flow field and the fractal dimension, and the computation scheme of volume flow distribution using box-counting method. One-dimensional model of cerebral vessel with considering tree structure was established.
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Tsutomu TAJIKAWA, Kenkichi OHBA, Takaya Ohno, Yuya Imamura
Article type: Article
Session ID: 707
Published: August 02, 2008
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In a human body, erythrocytes deform highly and can smoothly pass capillaries of which diameters are narrower than the cells'. Since capillaries connect all organs in a body, decrease in erythrocytes deformability causes several diseases. Therefore it is very important to evaluate the dynamic deformability of the erythrocyte at the microcirculation level. In this research, we produced a micro channel army with a 5μm×5μm square cross section of 100μm in length on the silicon substraight to simulate capillaries. After whole blood was centrifuged and erythrocytes were separated from plasma, the erythrocytes were diluted with autologous plasma by a hematocrit of 10%. This suspension was made to flow through the micro channels. Erythrocyte was observed using a high-speed video camera each day during preservation period. As a result, the time fluctuations of compressive strain of the RBCs agree with the theoretical curve of first-order lag element as a viscoelastic Kelvin model.
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Yuji SHIMOGONYA, Takuji ISHIKAWA, Yohsuke IMAI, Daisuke MORI, Takami Y ...
Article type: Article
Session ID: 708
Published: August 02, 2008
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We proposed a new hemodynamic indicator for the initiation of cerebral aneurysms, defined by the temporal fluctuations of tension/compression forces acting on endothelial cells. We calculated the proposed hemodynamic indicator and other three hemodynamic quantities (time-averaged wall shear stress (WSS), time-averaged spatial WSS gradient (SWSSG), and potential aneurysm formation indicator (AFI)) for a patient-specific geometry before aneurysm formation by means of computational fluid dynamics technique. The results showed that only the proposed hemodynamic indicator had a significant correlation with the location of aneurysm formation. Our findings suggest that the proposed indicator might be a prospective hemodynamic indicator for the initiation of cerebral aneurysms.
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Ken-ichi FUNAZAKI, Hirotada ENDOH, Masahiro HIGASHI
Article type: Article
Session ID: 709
Published: August 02, 2008
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A computational fluid dynamics approach is presented to simulate the blood flow in the human cerebral arteries including the peripheral vessels. The difficulty to determine the boundary conditions at the truncated position is overcome by using modeled peripheral vessels. The method is applied to the simulation of realistic 3-D Circle of Willis model that is reconstructed from a computed tomography image. Results of the simulation such as prescribed outlet pressure of 3-D model and the number of bifurcations are compared with some empirical data and have turned out to be in reasonable agreement between both of them.
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Naoyuki Yokoyama, Satoshi Waguri, Shinya Machida, Hideyuki Osawa, Kazu ...
Article type: Article
Session ID: 710
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Today, Mechanical Circulatory Support (MCS) is indispensable for treatment of patients with serious heart failure, not only the adult patients but also infants and children. The MCS can be utilized for applications including destination therapy (DT)/bridge to transplantation (BTT)/recovery oriented assistance with new medical treatment. In Japan, however, we do not have MCS devices suitable for Pediatric circulatory support. In this study, we have developed a tiny rotary blood pump (TinyPump VAD) with extremely small priming volume intended for circulatory support in children and infants. TinyPump VAD consists of a 6-vane impeller integrated with a direct drive motor with its diameter and height being 58mm and 35mm, and the priming volume of 6.5mL. The TinyPump VAD has favorable features as an implantable Pediatric MCS.
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Hajime SUGIUCHI, Satoshi MURAMATSU
Article type: Article
Session ID: 711
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Human hand is one of the best manipulators existing now. When we designing Robot hands, it is available that imitates Human's one. So we made a "Dynamics simulator by the detail human model" that Musculotendon model based on real human, and Iooked at its behavior. In this way we try to know characteristics and construction of Human hand. In our model musculotendon have branch. At the branch point muscle tension divided. And behavior of hand decided by that. But position of branch point move. So in this paper we show the behavior of branch in extensor digitorum that is affectec by 1st Lumblical as an example.
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Yu Moriwaki, Nobuo Sakai, Yoshinori Sawae, Teruo Murakami
Article type: Article
Session ID: 712
Published: August 02, 2008
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The human elbow joint has two degrees of freedom. Especially, wide range for the rotation of the forearm (pronation-supination) is attained, because of the sophisticated complexity of the human elbow joint. The elucidation of its mechanism is useful for medical evaluation and application to welfare devices. The purpose of the study is to develop the arm model that imitates the musculo -skeletal system of human elbow joint. In this paper, we made a computational model with a bionic elbow joint and evaluated the mobility of the arm model.
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Kentaro ARIHARA, Jiro SAKAMOTO
Article type: Article
Session ID: 713
Published: August 02, 2008
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The giraffe is under severe mechanical condition caused by the own special proportion. Several mechanical adaptations have been mentioned about giraffe's body. In particular, giraffe's neck can carry large moment and move flexibly. Both of high strength and high flexibility is achieved on the structure of giraffe's long neck. We focused mechanical strength of giraffes neck. We studied structural characteristic of the giraffe's cervical vertebra and analyzed stress distribution of the vertebra by FEM based on CT image to consider its mechanical adaptation. In addition, we analyzed stress distribution of the human's lumber vertebra to compare with one of the giraffe's cervical vertebra.
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Naomichi TOMINAGA, Hidetoshi KOBAYASHI, Keitaro HORIKAWA, Keiko WATANA ...
Article type: Article
Session ID: 714
Published: August 02, 2008
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Mimosa pudica, commonly called as sensitive plant, folds quickly its leaflets in response to an external stimulus. In order to obtain any innovative ideas for artificial structures, we measured the geometry of sensitive plant leaves and observed their folding motion. Numerical simulation using leaf model based on the optical measurement was also perfumed. It was found that the total kinetic energy of leaflets for fully unfolding increased with the increase of vein angle and aspect ratio of leaflet. However, the bending stress of vein at the fixed end dramatically decreased with increasing the aspect ratio
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Takaaki SATO, Hitoshi MIYAKE
Article type: Article
Session ID: 715
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The muscle spindle, as a sensor in vivo, has an interesting structure. So we studied that and developed a new loadecel. That is, a linear stage and tensiometer were combined for a prototype tensiometer. But it did not have range changeable mechanism. So a muscle spindle and y -motor neuron mimetic new model with range changeable mechanism was developed.
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Takahiro Ogura, Akitoshi ITOH
Article type: Article
Session ID: 716
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In this research, the possibility of motor-spring series connection type biomimetic actuator was investigated. The structure of the actuator is based on the author's one joint type actuator. In this actuator, the spring connected between the joint and the motor makes a role of tendon for animal's muscle-skeleton system. Three joints of the same constraction of former one joint type actuator were connected in series to make a leg. A numerical model of the actuator has been constructing now. A simple jumping experiment was enforced and some factors to improve in this system was found from the experiment.
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Masayuki KIKUDA, Ryou KATAYOSE, Tonau NAKAI, Tomonobu GOTO
Article type: Article
Session ID: 717
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This study deals with the motion of a singly flagellated bacterium swimming near a rigid surface. We have developed a method to produce three dimensional orientations of a cell as well as its trajectory from two dimensional images obtained by microscopy. The motion of a cell is observed from the direction parallel to the surface. The orientation is calculated from the positions of the front and rear ends of the cell body, which is like a rod with the thickness, in the x-z plane. Assuming that the cell swims in the direction of the axis of its rod like cell body, we have constructed the trajectory of the cell swimming backward which perfonned rotary motion near a rigid surface.
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Ryo KATAYOSE, Masayuki KIKUDA, Tonau NAKAI, Tomonobu GOTO
Article type: Article
Session ID: 718
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This study deals with the influence of a rigid surface on the motion of singly flagellated bacteria. We have developed a method to measure the distance between a cell and a surface utilizing the blurring of microscopic images out of focus, the degree of which is well quantified in terms of gradation sequence in grayscale. This method reveals the dependence of the swimming trajectory of a cell on the distance from the surface; in the range within 1.0 micrometers from the surface, most of the backwardly swimming cells draw circular trajectories, while they draw straight trajectories out of this range.
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Naoki ONO, Hirotaka FUKUSHIMA
Article type: Article
Session ID: 719
Published: August 02, 2008
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To investigate the driving force caused by motion of flagellum, the authors made the enlarged flagellum models which move in highly viscous liquid and measured the driving forces. The size and moving speed of the flagellum models were enlarged and determined according to scaling law. Reciprocal motion type and rotary motion type were prepared as test models, and the comparison was made in the same Reynolds number condition and in the same imposed power condition. As a result, rotary motion generated bigger force in the same Reynolds number condition, and reciprocal motion generated bigger force in the same power condition.
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Hirotomo HISAMA, Masaki KOMATSU YOSHIDA, Akitoshi ITOH
Article type: Article
Session ID: 720
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The authors have been developing the micro manipulation system using motion controlled microorganisms. Paramecium was used as a manipulator. Motion control was done by applying the negative galvano-taxis. Since the Paramecium's head is smooth round shape, it is difficult to transduce its force to the object effectively. Therefore, an attachment device for an operation tool of Paramecium has been developed. The authors have succeeded to attach an operational tool to the paramecium. It made the object transportation easier. The attachment of operation tool, however, was very difficult and the transportation experiment with operational tool have not reproduced during 3 years. In this paper, the problems for attaching the tool to Paramecium was searched according to the shape of the tool, holding pipette, attaching method, transration method to the experimental pool.
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Yukiya GOTO, Manabu ONO, Shigeo KATO
Article type: Article
Session ID: 721
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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We have many small diameter pipes that are gas or water pipes for individual or corporate houses and boilers or hot water pipes for industries. They must be periodically inspected in order to protect the accident previously. Diameters of these pipes are different at the place where pipes change from the main to the branch and a step comes here. The inspection robot for these pipes must move different diameter and go over the step. We propose a mobile robot that imitates the moving of a green caterpillar. The robot is constructed by the eight parallel rubber bellows and three suction brakes. The fabricated mobile robot was confirmed to move in different diameter pipes whose diameters are more than 70 mm. Its traction force was 20 N.
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Daisuke HOSOKAWA, Hirohisa MORIKAWA, Takuji ISHIKAWA, Yohsuke IMAI, Da ...
Article type: Article
Session ID: 722
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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A capsule endoscope is recently developed for the observation of the digestive system because digestive diseases particularly cancers very frequently occur and became fatal. Despite many advantages, the capsule endoscope has some limitations in the diagnosis, since it only moves passively by the peristaltic motion of the intestine. In order to overcome this problem, locomotive functions are expected to the capsule endoscope. In this study, we report a mechanical crawler system mimicking the pedal locomotion of snails for such a capsule endoscope. The crawler we developed has four joints, five segments and two suction cups. In locomotion experiments on a horizontal plane and on an inclined plane of 10 degrees, we confirmed that the developed crawler could locomote at the speed of 3 mm/s.
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Yuichi NAKAZATO, Kenichi TUBOTA, Hao LIU
Article type: Article
Session ID: 723
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Humming birds usually show similar features in size and flapping wing kinematics compared with insects but discrepancy in aerodynamic performance. In this study, we construct a realistic morphological and kinematic model of rufous hummingbird (Selasphorus rufus) for the computational fluid dynamic (CFD) study of hovering aerodynamics. We present results of the near-and far-field vortex flow structures around the animal in hovering, and further discuss about their relationship with the lift generation mechanisms.
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Masateru MAEDA, Hao LIU
Article type: Article
Session ID: 724
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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We have constructed a rigid-body dynamics solver intending to combine it with an in-house flow solver tailored for flapping-wing flyers. The dynamics solver developed is designed for a 6 DoF body. The attitude of the body is described with the Euler parameters in order to circumvent the difficulties that might be encountered when using the Euler angles. Using the solver, we carry out the flow field calculation which is coupled with the flight dynamics.
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Satoshi NAGATA, Masahiro WATANABE, Kensuke HARA, Hideaki TANAKA
Article type: Article
Session ID: 725
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This paper deals with an experimental study of a self excited aquatic propulsion mechanism with elastically supported parallel two oscillating hydrofoils. In the experiment, the propulsion force and side force generated by the waving motion of two wings are examined in stationary water. The propulsion force is examined with changing the frequency of the motor, phase angle, feed back gain and the spring stiffness for evaluation of propulsion performance of the mechanism.
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Shota NISHIMURA, Itsuro HONDA, Osamu KAWANAMI, Yousuke KAWASHIMA
Article type: Article
Session ID: 726
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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A jet stream is caused by oscillating an elastically airfoil and propulsion occurs. This propulsion is related to the modulus of elasticity. But until now, there is not an analysis with considering interaction between the elastic object and fluid. In this papar, we developed FDM-FEM coupling method wichi is satisfied with conservative of momentum. And we investigate the relationship between the modulus of elasticity and the velocity of a jet flow for airfoil by numerical analysis. Moreover, we investigate the relationship between the modulus of elasticity and the velocity of a jet flow for plate by numerical analysis. By compare the velocity increment obtained in the each result in these two cases, there is an interesting finding.
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Naotaka KATASE, Akitoshi ITOH
Article type: Article
Session ID: 727
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The authers have been developing oscillating fin propulsion type fish robots. The prototype of these robots is Tuna. In this study, a real tuna's caudal fin was dissected and the structure was investigated. The dissection results showed that the tuna's caudal fin can generate the phase angle to produce the thrust force automatically. This function is realized passively by one spinal joint with large movable area and loosen ligaments on the joint. Therefore the tuna's phase angle can be produced after cutting off from dead tuna. A dead tuna's caudal fin was connected to our robot fish's oscillating tail and the thrust force was measured. A rigid type caudal fin with loosen ligaments is proposed for the robot fish. The detail will be presented.
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Takemi OZAWA, Motomu NAKASHIMA
Article type: Article
Session ID: 728
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The final goal of this study was to develop an above-knee prosthesis for swimming. As the first step for this goal, its structure was examined by simulation in this paper. The swimming human simulation model SWUM, which has been developed by the authors, was employed for the simulation. First, the phases of joint angle and torque at the knee and ankle were investigated with respect to a non-amputee swimmer. By this investigation, it was found that the phases of joint angle and torque are almost opposite both for the knee and ankle. This result suggests that the knee and ankle joint actuators can be replaced by rotational springs in the case of above-knee amputee. Therefore, a simulation in which the knee and ankle joint actuators of one-side limb are rotational springs was conducted. The resultant swimming motion was found to become sufficiently close to that of the non-amputee swimmer.
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Noriaki TABATA, Kousuke Iga, Hiromu HASHIMOTO
Article type: Article
Session ID: 729
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The purpose of this research is to characterize an aerodynamics of the flying Dragonfly. Visualization experiment is very effective way to characterize an aerodynamics. However it is difficult to conduct the experiment on naturally flying Dragonfly. So we develop the simulator which imitates Dragonfly's flying motion. At first, analyze the Dragonfly's wing motion both free flight and hovering to develop the simulator. Then, the simulator is designed and produced based on the analysis result. Finally, we analyze the simulator's motion and compare the simulator's motion to Dragonfly's.
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Kosuke IGA, Noriaki TABATA, Hiromu HASHIMOTO
Article type: Article
Session ID: 730
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This paper describes airflow visualization around the Dragonfly's wing in flapping motion. It was very difficult to know aerodynamic characteristics by 'using the conventional visualization technology when the Dragonfly is flying freely in nature. Therefore we developed the simulator and conduct flow visualization experiment by using it. By smoke-wire method, in the experiment, several types of wings are tested, such as natural wing, coated paper wing, wing that pattern veins of wings and the influence of the deformation. And face structure of wings are clarified.
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Hiroshi NAKAI, Masahiro WATANABE, Hideaki TANAKA, Kensuke HARA
Article type: Article
Session ID: 731
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This paper deals with an experimental study on a self-excited flapping mechanism of flexible wings which mimicked a flight insect for fluid in low Reynolds number. The vibration (flapping motion) of the flexible wings is excited by the velocity feedback control with variable gain. This driving system follows the natural frequency change of the flexible wings automatically. And this driving system keeps arbitrary vibration amplitude by changing a velocity feedback gain. The velocity feedback gain is controlled by amplitude deviation. The propulsion force generated by the self-excited flapping wings is measured, and the performance of propulsion force is examined experimentally.
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Tadatsugu Imura, Masaki FUCHIWAKI, Kazuhiro TANAKA
Article type: Article
Session ID: 732
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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A number of researchers have attempted to develop small flap flying objects and MAV with various actuators and devices however they have not reached practical use at the present time. One of the reasons is that flying mechanism of birds and insects has not been clarified sufficiently. In this study, we evaluate dynamic behaviors of a wing observed from the butterfly's viewpoint in its flight. We conduct a flight observation experiment of Cynthia cardui performing a free flight and fixed flight and an image analysis and calculate flapping angles, lead-lag angle and feathering angles of the butterfly performing flapping flight to clarify the relation between them.
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Yusuke OSUMI, Ken-ichi TSUBOTA, Hao LIU
Article type: Article
Session ID: 733
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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It is known that conventional aerodynamic theories do not work for micro air vehicles (MAVs); and the low-Reynolds number aerodynamics in particular relating to flight mechanisms of insects and birds has been an active and interdisciplinary area. We have developed two types of four-winged prototype ornithopters. One has the "X-wings" similar to the Delfly (upper left wing and lower right are connected, so are lower left and upper right), whereas the other has the "Double L-wings" (upper and lower ipsilateral wing flap together while maintaining a right angle). The X-wings 'clap and fling' at both sides of the body; the Double L-wings clap and fling above the body. In this study we show experimental results on the aerodynamic performances of the two vehicles and further discuss how the transmission mechanism affects the force generation.
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Shinichiro ITO
Article type: Article
Session ID: 734
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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It is well-known that the flapping sound of owl wings is smaller than that of other birds. Fine serration at equal spacing can be found in the leading edge of the primary feathers (remidges) of owl wings, and it seems that it has brought the silencing effect. Paying attention to the owl's posture during capturing games, the author considered that the effect of serration brought not only damping sound but also change of the aerodynamic characteristic of a wing. By attaching a jig saw blade, different numbers of cutting teeth which imitated serration to the leading edge in a laminar wing, the aerodynamic characteristics of an aerofoil were measured and the flow field around the aerofoil was also visualized. The author confirmed that lift force was maintainable by larger angle of attack than the prototype wing in low Reynolds numbers.
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Na GAO, Kenichi tsubota, Hao LIU
Article type: Article
Session ID: 735
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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A numerical study of dynamic flight stability of a hovering hawkmoth and fruitfly are presented, respectively. The method of computational fluid dynamics (CFD) is used to compute the aerodynamic derivatives of the aerodynamic forces and pitching moment in response with a series of small disturbances and the techniques of eigenvalue and eigenvector analysis is used for solving the equations of motion. In the longitudinal disturbance motion, three natural modes are identified which indicates that a hawkmoth hovering flight is stable, while a fruitfly hovering flight is unstable. In addition, the time-response analysis of the simulation is shown here, which indicates the trajectory of the disturbance values in respect of time.
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Takashi MORIYAMA, Kenichi TUBOTA, Hao LIU
Article type: Article
Session ID: 736
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Insects are master in maneuvering. Here we present an integrated study of flapping flight stability in a forward flight of hawkmoth by combing a biology-inspired dynamic flight simulator and a recently developed optimal algorithm for flapping wing kinematics. We first compute the vortex flows around a wing-body hawkmoth model, the aerodynamic forces including the lift and drag as well as three moment components. Then, an optimal algorithm is introduced to optimize the flapping wing kinematics so as to realize a trimmed (or balanced) flapping flight mode that the lift is exactly equal to the weight while the drag vanishes at a constant, low and/or high flight speed including hovering. The computed results are compared with experimental data and validated to be reasonable; our results indicate that small variation in flapping wing kinematics may lead to significant change in the force generation.
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Tetsuya YOSHIIKE, Hirohisa MORIKAWA, Qilong Sun, Shunichi KOBAYASHI, M ...
Article type: Article
Session ID: 737
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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It is known that a dolphin swims fast and freely in water. The propulsive performance and the kinetic performance of the dolphin are one of great concern among researchers. We paid attention to the dolphin's tail flukes which has an important role to generate propulsive force. So the experiments on both the propulsive force of the outboard propulsor with the oscillating wing which is similar to the dolphin's tail flukes in shape and the velocity of a small boat equipped with the outboard propulsor were carried out. The propulsive performance of the wing was discussed compared with rectangular wings.
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Hirofumi KURIHARA, Katsuya NAGAYAMA, Takashi HONDA
Article type: Article
Session ID: 738
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The robot which operates at the black spot and medical field is operated by remote control. However, the most suitable swimming form and fin shape of such a robot is not yet elucidated. By using the visualization analysis, we optimized the tail and fins of the fish robot which drives by the magnetic field.
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