Summaries to Technical Papers of Annual Meeting, Japan Association for Wind Engineering
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Proceedings of Annual Meeting 2021
  • Daisuke Somekawa, Yumi Iida, Satoru Goto, Yoshiyuki Ono, Kiyotoshi Ots ...
    Pages 77-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    A wind tunnel experimental setup with a multi-fan, which is considered to be relatively easy to create unsteady airflow compared to a large fan, was used to reproduce natural wind fluctuations. In the absence of walls and ceiling of the wind tunnel, it was shown that the airflow equivalent to uniform flow and roughness category III was not very uniform except near the center of the turntable. However, it will be possible to reproduce the variation of natural wind by controlling the fan speed near the center of the turntable.

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  • Yoshiyuki Fugo, Tetsuro TAMURA, Daiki SATO, Akira KATSUMURA
    Pages 79-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    When performing layered wind power evaluation by simultaneous wind pressure measurement at multiple points, the measurement points are arranged discretely. Therefore, a discretization error occurs. Discretization error is evaluated by comparing it with an experiment using a device called a "balance". However, before making a wind pressure model, we need to know how many wind pressure measurement points should be installed for the complex shape of a real building.

    In this report, we will introduce a study using a wind pressure model in which measurement points are densely arranged. We focused on the top of the model and the two layers near the stagnation point. The effect of measurement point density on layer wind power and layer torsional moment was investigated. The target building has a flat shape. In order to obtain measurement accuracy in this building, it is necessary to arrange eight or more wind pressure measurement points on the long side.

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  • Kota Enoki, Takeshi Ishihara
    Pages 81-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    In wind energy projects, on-site measurements are conducted to evaluate the amount of resource or to ensure the conformity of site conditions for wind turbines. Sometime the missing of observation is compensated using the nearby observation by the MCP method. In general, the uncertainty of the MCP method can be examined during its construction stage of a prediction model. However, the method to estimate the accuracy of final product that is composed of observation and complementation by the MCP method is not clear. In this report, a formula to easily estimate this final observation accuracy is proposed and verified its validity by on-site measurement.

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  • Daichi Tanimoto
    Pages 83-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    As the length of bridges increases, the wind stability of the main towers is required. Currently, the bluff body with corner-cut are used for the main towers, but there are many unclear points as to why it suppresses the vibration of the main towers, and it is necessary to understand the flow around it. In this study, rectangular, corner-cut, and triangle corner-cut were compared using computational fluid dynamics analysis. It was found that the width of the separated flow was reduced in the bluff body with corner-cut and triangle corner-cut compared to the rectangular body and it causes that the pressure loss at the upper surface and wake was suppressed. It was also confirmed that the suppression of pressure loss contributed to the aerodynamic stability of the bluff body with corner-cut and triangle corner-cut. In this study, a comparison was made between the bluff body with corner-cut and triangle corner-cut, but no significant difference in aerodynamic characteristics was observed.

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  • Kazuyoshi Nishijima, Ryoichi Kamoshita
    Pages 85-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    Current state-of-the-art methodology for wind induced damage analysis employs, as wind hazard indicator, the wind speeds measured by nearby anemometers or the wind field obtained by reanalysis with a weather model. However, the physical parameter that directly affects wind damage is, except for flying debris induced damage, wind pressures acting on respective components of buildings. Thus, it is sound that wind pressure is employed as the wind hazard indicator in damage analyses. This study aims to develop a method to build wind pressure experiment models using point cloud data generated based on UAV aerial photos and a 3D printer, and then to investigate the validity of the estimated wind pressure coefficient obtained using such models.

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  • Koji Sassa, Momoka Aoyagi
    Pages 87-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    We made laboratory experment of tornadogenesis, in order to clarify the generation process of tornadoes when the cold outflow intrudes the updraft region. From the experimental results, we found that the generation process of the tornado is separated to three stages; (1)formation of updraft column with weak rotation, (2)cold outflow turning around the updraft column, and (3)formation of tornado-like vortex. These stages correspond to those of actually observed waterspout. The generation process of tornado was found to be affected by the slight change of flow environments. In some cases, the tornado could not be formed because of such effects.

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  • Yumi Iida, Daisuke Somekawa, Satoru Goto, Yoshiyuki Ono, Kiyotoshi ...
    Pages 89-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    Damages by gusts such as tornados have increased, and preventive measures are urgently required. For that purpose, the basic characteristics of these gusts must be clarified.

    Therefore, the tornado-like wind was reproduced by the tornado-like wind simulator and the three components of the wind speed were measured by the three-dimensional PIV. In this study, we reproduced tornado-like flows with different swirl ratios by changing the height between the floor and the inlet and angles of the guide vane, and then organized the relationship between the swirl ratio and the velocity distribution of the tornado-like flow. In addition, by moving the tornado device, the effect of the movement of the tornado on the tornado-like flow was clarified.

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  • Takashi Maruyama, Tetsuya TAKEMI, Hiroyuki YAMADA, Kosei YAMAGUCHI
    Pages 91-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    Wind turbulent generated by surface roughness use to be considered for the strong wind characteristics causing damage to buildings and houses. Resent observations with newly improving measuring devises clarify the extreme meteorological phenomena such as down burst, tornado or gust front and so on, which results that to evaluate the strong wind hazard considering the wind gust caused by the convection under cumulus cloud is essential for the accurate damage prediction. Therefore, we conducted the wind observation by using doppler lidar and obtained the strong wind records under the front passage. The wind characteristics of surface boundary layer under convective cumulus cloud were examined.

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  • Masaru Ishikawa, Yasuyuki Ishida, Akashi Mochida
    Pages 93-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    The urban morphology has strong relationships not only with pedestrian wind environment within the focused urban district but also with that in areas leeward of the focused area. The consumption of more momentum and kinetic energy of the wind leads to decreased wind velocity in the leeward areas. In previous studies, the magnitudes of the negative effects have been evaluated with the drag force, which represents the loss of momentum, and the energy dissipation rate, which represents the loss of kinetic energy, within the focused area. However, the difference in these implications has not been discussed well. In this study, the relationship between drag force and energy dissipation rate was clarified.

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  • Yoshihide Tominaga, Mohammadreza Shirzadi
    Pages 95-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    In this study, we proposed a building shape optimization method that minimizes the effect of a high-rise building on wind velocity accerelation by complementary use of RANS (low-fidelity) and LES (high-fidelity) models. The effectiveness of the method is further examined by applying it to pedestrian wind environment problem in an idealized city block. The incremental performance value (IPV) of RANS and LES are in good agreement when the wind speed increase evaluated at K>1.1. On the other hand, when K>1.3, the IPV by LES was larger than that by RANS. The difference was especially large when the wind direction is 0°. This is due to the fact that SRANS does not reproduce the high wind speed peaks that occur near the upwind cavity and the side of the high-rise building in RANS. However, the trend of IPV with the change in wind direction was well captured.

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  • Guowei Qian, Yunpeng Song, Takeshi Ishihara
    Pages 97-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    The present study in part 1 is to develop a Large Eddy Simulation (LES) framework for wind turbine wake and power prediction by incorporating control algorithm and blade rotation. Firstly, the torque, pitch and yaw control is implemented in LES, and the predicted thrust force and power generation under varying wind speed and wind direction show good agreement with those calculated by the aeroelastic model FAST. Subsequently, three-dimensional flow field visualization and spectrum analysis are performed, and the results demonstrate that the blade rotation-induced aerodynamic effect is reproduced by using the Actuator Line Model (ALM).

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  • Part 2: Coriolis force effects and its validation by filed measurement
    Yunpeng Song, Guowei Qian, Takeshi Ishihara
    Pages 99-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    The present study of part 2 is to apply the developed Large Eddy Simulation (LES) framework to a real wind turbine. Firstly, the turbulent inflow is generated by using the measred data from met mast, and then the control signal and power are predicted and its accuracy is validated by SCADA data. Finally, the wake flow is simulated by considering Coriolis force effects and shows a favorable agreement with those measured by LiDAR.

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  • Takanori UCHIDA, Kenji ONO, Akiyoshi IIDA, Shinobu YOSHIMURA, Chisa ...
    Pages 101-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    In this study, we introduce the numerical results of wind turbine wake simulation from the wind tunnel model scale to the actual scale using the supercomputer version RIAM-COMPACT.

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  • Yong Chul Kim
    Pages 103-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    Traditionally wind turbines have been mounted on circular towers. However, weaknesses of these towers with upsizing of wind turbines have become apparent. Their main weaknesses include problems related to manufacture, low compressive and buckling strength and problems related to their land transportation. To overcome these problems, the concept of site-assembled modular towers with polygonal cross-sections is proposed, but no systematic studies have investigated the effects of polygonal towers on the aerodynamic performance of a wind turbine. In the present study, the effects of cross-sectional shape of the tower on a 5MW pitch-control wind turbine were investigated by wind tunnel tests. Seven polygonal cross-sections were considered: square, square helical (helical angle 180°), octagon, decagon, dodecagon, tetradecagon and circular.

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  • Hisato Matsumiya, Saki Taruishi, Tomomi Ishikawa
    Pages 105-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    This paper presents the effects of structural and aerodynamic non-linearity and resonance component on dynamic wind load and response on overhead wires under fluctuating winds. Time-history response analyses were performed using a finite element model of an overhead wire. Various approaches to modelling of the structure and the aerodynamic force were taken to evaluate the effects of structural and aerodynamic nonlinearity. In addition, the effect of the resonance component was evaluated through a comparison with the results of dynamic and quasi-static analyses.

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  • Kichiro Kimura, Lisa Kai, Katsutoshi Ohdo, Hiroki Takahashi
    Pages 107-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    Scaffolding with noise barrier panels is often used for demolition works of old buildings. However, large wind loading due to strong wind may act because the panels are difficult to be removed beforehand, and the wind force distribution was measured in a wind tunnel test. Two types of building model, one is before demolition work and the other is during U-shape in plan. The obtained forces were non-dimensionalized as the instant force coefficients and were compared with values by a guideline. For the panels around U-shape model, the instant force coefficients sometimes took larger absolute values than the guideline particularly around the opening possibly due to the effects of flow separation at the end of the panel.

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  • Saki Taruishi, Hisato Matsumiya, Naohiro Souda
    Pages 109-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    A wind tunnel test and a single-degree-of-freedom response analysis using quasi-steady aerodynamic force were carried out to evaluate the effect of the vibrating direction on occurrence condition of aerodynamic unstable vibration of a cylinder with a rivulet. The mechanism can be evaluated by the analysis because the analytical results well included the experimental results. The excitation effect of lift force becomes larger as the vibration direction is closer to the wind orthogonal direction. The damping effect of drag force is small when the cylinder vibrates diagonally upwards towards the wind. As a result, the largest vibration occurred when the cylinder vibrates slightly diagonally upwards towards the wind.

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  • Yuxuan Yan, Tomomi YAGI, Kyohei NOGUCHI, Kazuki TAKAHASHI
    Pages 111-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    Aerodynamic instabilities of a bridge girder is sensitive to bridge attachments such as handrails. But it is still lacking an in-depth study on the effect of the handrail details and layout on vortex-induced vibration (VIV). In this study, Spring-supported free-vibration wind tunnel tests were conducted to investigate the effect of handrails on VIV response of a single box girder. Experimental results shows that increasing the side ratio of the handrail middle bar decrease the VIV amplitude. Meanwhile, setting a grid handrail or a solid handrail at the leeward side is quite effective in improving the VIV instability.

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  • Nozomi Suyama, Hiroshi Yamaguchi, Hiroo Inoue
    Pages 113-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    In order to improve efficiency and safety, a wind-turbine power generator includes a blade pitch angle and yawing control function. Various control methods have been proposed, among others there is the control method which has a condition of the trailing edge into the wind for reducing extreme loads. Recently the size of wind-turbine power generator is getting larger, the use of such control method is expected to increase further in the future. However, there has been little report on aerodynamic characteristics of blade at angle of attack around 180°.

    In this study, we carried out a spring supported test by using two-dimensional model. This report describes a dynamic characteristic of two blades (NACA0012, NB18 which is asymmetrical blade) at angle of attack 172°,180°, and 188°. These results showed some differences in the presence of flutter and the critical wind speed. Moreover, the distinguishing characteristic was obtained in case of NACA0012 at angle of attack of 180° when the single degree of freedom system was used.

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  • Hiroshi Noda, Rajat Mittal, Jung-Hee Seo, Karthik Menon
    Pages 115-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    In this study, the energy transfer of wind force to vibrating 2D rectangular cylinder was calculated using the computational fluid dynamics of forced excitation vibration. The vibration amplitudes of aero elastic vibrations of 2D rectangular cylinders such as vortex excitation and galloping were predicted from an energy map consisting of energy transfer with various vibration periods and amplitudes. In addition, the properties of aero elastic vibrations were considered based on the energy map. 2D rectangular cylinder with a side length ratio of 2 was the target in current study

    The positive and negative of the energy transfer obtained from calculation of forced vibration match with those of the velocity in-phase component of the wind force coefficient.In addition, the positive and negative of the phase angle between wind force and response displacement were almost the same. It can be said that the same informations are provided for these three physical quantities. From the energy map, the vibration amplitude of aero elastic vibration can be predicted in case that structural damping is 0.

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  • Hiroshi Miyamoto, Tomomi Yagi, Kyohei Noguchi, Soichiro Yamamoto, Atus ...
    Pages 117-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    It is known that the side opening affects the aerodynamic vibration characteristics in a rectangular cylinder with B/D = 2, which imitates a butterfly web bridge. Therefore, we conducted experiment to investigate the aerodynamic vibration characteristics of a rectangular cylinder with side openings. We used two different opening shapes. One is opening shape with alternating distribution of openings and closures in the span direction, and the other is two-dimensional opening shape that eliminates structural three-dimensionality. As a result, it was found that the larger the opening ratio, the higher the wind speed at which galloping occurs, and the excitation force of the galloping reached a maximum value at a certain opening ratio.

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  • Yuki SAKAI
    Pages 119-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    In the current wind-resistant design of a building, the elastic design is based on the equivalent static design method, which confirms the safety of the building when the wind load is applied statically. Therefore, it is rare for the design to take into account the cyclic loading caused by fluctuating wind force and its action time. In recent years, buildings are becoming taller and longer in service life, and it is expected that fatigue damage evaluation of components and cladding under cyclic wind loading will become more important. In this study, fatigue damage evaluation of vertical fins on exterior walls of a building for a service life of 100 years is conducted based on typhoon simulation and LES. In addition, POD analysis is performed on the fluctuating wind pressure obtained by LES to confirm the effect of resynthesized waveform on the fatigue damage level.

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  • Yoshiyuki Ono, Tetsuro Tamura
    Pages 121-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    In this paper, the LES method is applied to the flow around a three-dimensional square in boundary layer turbulence in order to study the effects of the roughness block located on the upwind region on the aerodynamic characteristics of a square cylinder. As a result, the fluctuating component in the transverse direction in the bottom region of a cylinder tend to increase in the case without the roughness blocks compared with the case existing the roughness blocks. The lack of the roughness block in upwind region cause the oncoming turbulence to be decreased and the negative pressure region of the side of the cylinder to be wide by the influence of vortices shedding in the wake.

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  • Kazutoshi Matsuda, Kusuo Kato, Kenta Shigetomi, Nade Cao, Sai Yokota
    Pages 123-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    This study focuses on motion-induced vortex vibration occurring from Vcr=0.83B/D. This is an experimental study of the effect of the change in cross-sectional shape on the vortex-induced vibration response characteristics when the chamfer angle is gradually changed. As a result, when the angle is less than 5 deg., separated vortex from leading edge are generated on the upper and lower surfaces of the cross section and motion-induced vortex vibration occurs, but when the angle is 10, 15 deg., the generation of separated vortex from leading edge weakens, and instead Kármán vortex generated from the trailing edge gradually strengthened. Therefore, the vibration is likely to change to Kármán-vortex vibration from motion-induced vortex vibration as the chamfer angle θ is increasing.

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  • Thu Minh Dao, Tomomi Yagi, Kyohei Noguchi, Haruki Fukushima, Tung Quan ...
    Pages 125-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    A cable attached with 12 spiral protuberances has been shown to experience drag crisis at Re = 1.3x10 4 -2.3x10 4, a much lower Reynolds number than that of a smooth cable. This study aimed at describing how the flow around the modified cable would develop during drag crisis under the influence of the spiral protuberances by studying the surface pressure on the cable in normal flow and skew It has been revealed that the suppression of alternating vortex shedding was closely associated with drag crisis. Beyond drag crisis region, flow patterns still experienced drastic changes in time and space. However, drag coefficient stayed constant. In 45-degere yawing condition, pressure fluctuation became even more suppressed so that the flow seemed to resume its 2 dimensionality.

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  • Yuta Tsubokura, Kyohei Noguchi, Tomomi Yagi
    Pages 127-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    The dry gauze method, which uses gauze embedded in a wooden frame, is often used to evaluate the amount of airborne salt. However, the scattering behavior of particles around the collection device and the deposition mechanism to the gauze fibers has not been studied in detail. In this study, the particle collection efficiency of gauze fiber was investigated based on the flow fields around the circular cylinders in cruciform arrangement by CFD. The results showed that the particle collection efficiency of the circular cylinder can be estimated from the amount of pressure loss that occurs when the fluid passes through the cylinder.

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  • Takafumi Gotoh, Tomomi Yagi, Tomoya Okunishi, Hisato Matsumiya, Kyohei ...
    Pages 129-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    Large-amplitude self-induced aerodynamic vibrations of bluff cylinders are perhaps explained by the unsteady aerodynamic forces determined by the relative angle of attack and the time derivative of it in comparatively higher reduced wind velocity region. The authors have obtained this aerodynamic force by measuring the aerodynamic force of continuously rotating body, and have shown that the torsional 1DOF (degree-of-freedom) vibration can be explained. In this study, the validity and range of the vertical 1DOF vibration that can be expressed by the aerodynamic force of continuously rotating body were investigated using a rectangular section with a side ratio B/D = 2, from high to low reduced wind velocity region. As a result, the validity was shown in the high reduced wind velocity region and the large amplitude region of the low reduced wind velocity region. It was also shown that even in the low reduced wind velocity and small amplitude region, the aerodynamic characteristics during vertical 1DOF vibration can be explained by the relative angle of attack and the time derivative of it.

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  • Kyohei Noguchi, Yuki Tsuda, Yuta Tsubokura, Tomomi Yagi
    Pages 131-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    Evaluating salt amounts adhering to bridge surfaces is important for effective maintenance. However, mechanisms of transportation and adhesion of salt particles have not been sufficiently investigated yet. The authors studied how particles were affected by flows and delivered to surfaces using rectangular prisms with different side ratios by CFD. The transportation process of particles depended on the shape of a structure, which resulted in a unique distribution of the salt amount. Besides, the spatial gradient of the time-averaged pressure coefficient on structural surfaces was investigated. It was clarified that it was probably able to evaluate the adhesion amount of salt accurately.

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  • Seiji Nakato
    Pages 133-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    A vertical splitter plate was installed in the wake region of a rectangular cylinder, and the effect of the position in the axial model direction on wind pressure characteristics was investigated. For B/D = 1, the coherence decreased when the vertical plate was located near the center of the two pressure points. For B/D = 3, there was an effect of splitter plate on the correlation when the distance between the model and splitter plate was narrow, but there was little effect when the distance was wider. It was suggested that the correlation in the wake region does not affect the correlation wind pressure, and the influence of the flow field around the model is large.

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  • Shuichi Itoh, Minoru Noda
    Pages 135-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    The phrase "a disaster you have never experienced" in the 2020 Typhoon No. 10 report is strange. In other words, past experiences differ depending on where the recipient of the information lives and the length of life, so it is not possible to convey the information accurately. To solve this problem, it is necessary to convey the expected wind speed in the form of frequency of occurrence.

    This research proposes that the 100-year return period expected wind speed map and the 500-year return period expected wind speed map provided in the building load guideline are digitized as GIS polygon information, and the frequency of occurrence of a certain wind speed can be provided in the form of a return period map.

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  • Hinano Yamada, Minoru Noda
    Pages 137-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    In this study, the wind direction was divided into 64 directions, and the influence of the surrounding topography on the flow field at a specific point in the hilly area was examined by numerical fluid simulation using a standard k-ε model based on RANS. As a result, it was confirmed that hills and valleys affected the flow field. In addition, by subdividing the wind direction, detailed changes in the wind speed ratio distribution with respect to changes in the wind direction were obtained, and two typical types of wind speed ratio distributions could be confirmed. Furthermore, many results suggest that the basic wind speed ratio distribution is characterized by terrain within a radius of 1 km, and it was found that distant terrain may strongly affect the wind speed ratio in a specific wind direction.

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  • Haruo Oda, Wataru Mashiko, Eriko Tomokiyo, Minoru Noda
    Pages 139-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    In this study, the application of the Weibull distribution based on the weakest link model to the distribution of strong wind damage in southern Osaka Prefecture in Typhoon Jebi, that occurred in 2018, .was examined. As a result of dividing the disaster area into orthogonal grids and analyzing it, it was found that the cumulative damage probability based on the maximum wind speed squared value for each housing density follows the Weibull distribution and each Weibull parameters were decided by housing density. Moreover, It was shown that the damage probability model using this relationship matches the observed cumulative damage probability well. A, which is multiplied by the Weibull distribution, could be affected by the period from the disaster to the aeronautical survey.

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  • Yasuhiko Azegami, Hideyuki Tanaka, Quang-Van Doan, Hiroyuki Kusaka
    Pages 141-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    Numerical experiments under current and future climates using the pseudo global warming method for Typhoon Hagibis in 2019 were conducted. As a result, it was found that under future climate, the surface wind speed may increase by 10 m / s or more in coastal areas such as Chiba prefecture compared to the current climate (reproducibility experiment). In addition, in the area around Tokyo Station, the maximum value of the ground wind speed is 10 m / s or less in most areas in the current climate, but it can exceed 10 m / s in the future climate, and the wind speed can exceed 16 m / s depending on the location. From these results, it is possible that the damage caused by typhoons will increase in the future climate, and it is considered that further measures against strong winds will be required in advance.

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  • Yuki Takadate, Hitomitsu Kikitsu, Yasuo Okuda
    Pages 143-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    Based on recent wind disasters, Notification No. 109 issued by the Ministry of Construction (1971) in the Building Standards Law was revised on December 7, 2020 by the Ministry of Land, Infrastructure, Transport and Tourism. According to the revision, the roof tiles on a new building need to be fixed tightly with nails or screws as a fundamental rule from January 1, 2020. In addition, the fixing method for an existing building when extending or renovating was revised in the Notification No. 566 issued by the Ministry of Land, Infrastructure, Transport and Tourism (2005). Furthermore, the category of surface roughness for inside and outside city planning area specified in the Notification No. 1454 issued by the Ministry of Construction (2000) was revised. In the present paper, these notifications are described.

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  • Eriko Tomokiyo
    Pages 145-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    This paper reported the characteristics of residential and human damage caused by so-called ‘rain typhoons’, which accompanied by heavy rain, and ‘wind typhoons’ which with severe winds. It was found that the number of residential damage and casualty has not decreased much in recent years focusing on typhoons since 1991. The number of dead and injured people increased especially during ‘wind typhoons.’ During a ‘wind typhoon’ with little rainfall, some people work outdoors even under severe storms, which leads to the spread of human damage. It must be widely educated that you should not go outdoors to protect yourself in strong winds.

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  • Hiroki SATO
    Pages 147-
    Published: 2021
    Released: June 15, 2021
    CONFERENCE PROCEEDINGS FREE ACCESS

    Waterspouts sometimes make landing. Since surface roughness is different from land to the ocean, it is expected that strength and/or structure of vortices will change during the landfall.

    In this study, I have managed some LES simulation on non-uniform surface roughness plane. When the surface roughness is non-uniform, lower part of the vortices axis leaned. Especially, when swirl ratio is very small, vortex core is mainly consist of fluid which has passed over small roughness plane, which has lost less head than those on larger surface roughness plane. These non-uniformity of kinetic energy may affect the cyclostrophic balance of tornadoes.

    The goal of this study is to reveal what happens to a tornado during its landing process.

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