Measured values of 3 kinds of wind speed and direction meter which is used for meteorological observation are compared through wind tunnnel experiment under the same condition.
3 kinds measuring instruments are 3 cup type ,aerovane type and 3 dimensional ultra sonic wave type.

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Authors have carried out the wind field measurement in Tsukuba area, where is supposed to be flat field with rare topographic ups and downs. Doppler sodar in Building Research Institute(BRI) and anemometers in Meteorological Research Institute(MRI) are used for the measument and the latter is located about 10km to the south of the former. In this study, measurement results on March 3rd through 21th are discussed. As for the wind velocity and direction between two places, it is confirmed that there is a certain correlation. On the vertical profile of the wind velocity, averaged index of the power law in MRI is larger than that in BRI and depends on wind direction. The averaged index from northern wind is larger than that from western wind, which is probably because there is an urban area with middle-rise buildings to the north of MRI, while there is relatively rural distincts to the west of MRI. Cross-correlation coefficients obtained from every ten minutes' index of the power law of the each point result in getting maximum values at timelag of 10 through 20minutes, which means that it is useful to evaluate the profiles by considering wind with time scale of a few ten munites.

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It was reported that the annually averaged wind speed in Fukuoka is decreasing gradually after 1980. In this study, the relation between the decrease and the heat island effect has been investigated by means of data-analysis. In summer, a good correlation is seen between wind speed and temperature. It suggests that the local winds generated by a thermal convection become dominant. In winter, the convection dome formed by the heat island effect becomes stronger and makes the approach speed of winter monsoon weak. The decrease of the annually averaged wind speed after 1980 may be attributed to that of the winter monsoon.

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To evaluate the flight safety of the planned Aogashima Island heliport, local wind filed was investigated using the flight test and numerical simulation. In the flight test, atmospheric turbulence around the planned heliport was successfully measured using the National Aerospace Laboratory of Japan's research helicopter MuPAL-Epsilon. The numerical simulation conducted by the Japan Weather Association well explained the general characteristics of the local wind field. Using flight test and numerical simulation results, the wind field influence on the flight safety was correctly evaluated.

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For the rational assessment of wind load on structures or components, the wind directionality should be considered. For that purpose, It is nesessary to develop a new methodology for the more precise estimation of ground surface roughness. In this paper, the past researches are reviewed and their applicability is clarified.

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In order to evaluate the wind load effect considering the wind speed directionality, the wind speed probability and the directional wind speed-load effect relationship should be known. This paper proposes improved typhoon simulation, the so-called POD-based pressure model and hybrid use of observed records and calculated values. Directional wind speed probabilities are evaluated using an improved method for typhoon winds and a statistical method for non-typhoon winds. Directional wind speeds are evaluated considering the wind load effects of tall buildings.

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Typhoon simulation technique is used to simulate typhoon paths and predict their wind speed level. On the other hand, global warming effects are emphasized and simulated by many organizations. Increase of sea surface temperature (SST) is predicted and it may affect strength of typhoon, in turn, wind speed level. In this study, incorporating SST effects into typhoon simulation technique, changes of typhoon strength and wind speed level are studied.

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In this research, in order to generate the inflow turbulence, the turbulence parameters for velocities at recycle station are rescaled and introduced to the inlet boundary, while temperature is treated as a passive scalar. The generated inflow data for temperature as well as velocities are introduced into the main computational domain, where temperature is solved taking into consideration buoyancy effects. With this method, a long fetch is not necessary to simulate the spatially-developing boundary layer. We carry out LES analysis of the spatially-developing stable/unstable stratified turbulent boundary layers. We at first apply Lund's method to generate the inflow turbulence for stratified turbulent boundary layer. By using the generated inflow data, we can simulate the spatially-developing stable/unstable stratified turbulent boundary layers, and investigate the turbulence structure inside them, particularly in the outer part of stratified boundary layer where the flow around inversion layer intermittently interact with each other.

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For the estimation of urban air quality, it is important to predict turbulent flows over buildings and structures, which are densely arranged in the urban area, and to clarify the dispersion process in the surface layer over very roughened surface. In this paper, it is the objective to determine the characteristics of flow and dispersion which change by arranging scatteringly the roughness blocks after making a spatially developed turbulent boundary layer over rough-wall by using LES technique and the pseudo-periodic boundary conditions. Two LES cases (uniform (staggered) arrays and random arrays )are carried out. Consequently, near the roughness height, touchdown in random arrays is earlier than that in uniform (staggered) arrays because of the local characteristic of roughness blocks. On the other hand, in the upper part, although there is no clear difference of streamwise fluctuating velocity between uniform arrays case and random arrays case, a great difference of mean and fluctuating concentration between both cases arise.

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Roughness density is considered to be the most important factor to determine the mean wind velocity profile. In this study, we predicted the mean wind profile in two ways. One is by evaluating the roughness density and another is from the numerical results of LES. Comparison is carried out between the results.

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The Immersed Boundary Method (IBM) allows the computation of the flow around complex objects without requiring the grid lines to be aligned with the body surface. In this study, IBM is applied to Large Eddy Simulation of the wind flow field around the cluster of existing tall buildings, which faces in different directions each other. Firstly, the effect of the presence of buildings around the building under consideration is evaluated by comparing the computation of flow field around single and three buildings, under uniform inflow condition. Next, the importance of inflow condition to develop reliable computational code for wind resistant problems is discussed by comparing the results of computation around three buildings under turbulent boundary layer and uniform inflow condition.

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This study investigates the performance of the S-W model proposed by Nagano & Hattori, in predicting flow over two-dimensional slopes(up-slope and down-slope) with various slope inclinations.

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A turbulent flow over a two-dimensional steep hill was analyzed by large eddy simulations (LES). Here, two LES computations were carried out using two different sub-grid scale (SGS) models, i.e., non-Smagorinsky type eddy viscosity models proposed by Inagaki et al. (2002). The accuracy of these computations was assessed by comparing the results with those from an experiment by Ishihara and Hibi (1998).

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This study brings into focus the turbulent boundary layer flow over a two-dimensional hill, which has special characteristics near the hill with favorable or adverse pressure gradient and surface curvature effect. This kind of flow involves acceleration or deceleration, separation and reattachment. In this paper, we carried out direct numerical simulation (DNS) of unsteady flows over a two-dimensional steep hill for the oncoming boundary-layer turbulence. We investigated turbulence statistics of the computed flow over a steep hill, such as mean-flow, turbulence intensity and budget of turbulence energy.

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When an urban fire occurs under a strong wind, the induced thermal-plume generated from multiple houses on fire heats the distant houses and fosters the spread of fire. Moreover, it hinders the rescue, evacuation and fire-fighting. In order to establish the measures for preventing the spread of an urban fire and evaluating the risk in the evacuation area, it is essential to acquire the knowledge on the behavior of the leeward thermal plume generated from multiple houses.Therefore,this study aimed to propose the equation predicting the leeward thermal-plume distribution on the basis of findings from a series of model experiments in the fire wind tunnel. Assuming the initial stage of an urban fire, the experiments were carried out with the single, two sources.

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Trajectory of flying debris in an urban area strongly depends on the flow filed and the physical properties of the debris itself. In this study, the trajectories of spheres and rotating plates are predicted, by using the turbulence flow filed in an urban area (Kanda, Tokyo) obtained by LES. The results show that the debris in turbulent flow filed fly a longer distance than in uniform flow due to the large instantaneous wind pressure and velocity, and the rotating plates fly longer than spheres due to the existence the lift force.

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The paper reports some of the relation between residential damage and wind duration, which is based on wind data of NeWMeK and AMeDAS when Typhoon Bart passed through the Kyushu area. The longer wind duration suffers the more extensive residential damage in case of the mean wind of exceeding 25 m/s of the NeWMeK data or exceeding 20 m/s of the AMeDAS data. In contrast, when the mean wind speeds are not exceeding 25m/s and 20m/s respectively, the rate of damage becomes about 1% and damage doesn't increase. In case the wind speeds become higher, the shorter duration of wind speed brings the same damage rate. It is confirmed that the duration of wind speed influences strongly the increase of residential damage. We should investigate further the relation between the duration of wind speed and the residential damage.

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Wind force on a roof tile of an experimental house with a hipped roof was measured in natural wind. The objective of the measurements is to clear the condition and the mechanism of the instantaneous large peak lift on tiles, which causes the tiles to scatter. The measurements have done for two conditions; one is to seals an end of an eave and the other is not to seal that. The maximum peak lift occurs on the tile close to the eave when wind attacks nearly normal to the eave. When the peak lift occurs, the external pressure decreases very rapidly. Though, the internal pressure keeps its mean value in the batten space. When the space under the tile at the end of the eave seals, the internal pressure decreases simultaneously when the external pressure decreases rapidly. So, the peak lift becomes smaller for the case with the seal than that without the seal.

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As the first stage to predict the scatter of firebrand in urban fire, fire plum was simulated when there is a horizontal flow. The building was assumed to be wood, and a fire model which the carbon monoxide generated by the pyrolysis of wood combusts in the air is assumed was used. When assuming the loading of the combustible for each building roof is 35kg/m2, the amount of heat release from one burning building is 1.6 MW/m2. When inflow wind velocity is low comparatively, heat rising flow is significant, and when it is a strong wind, heat rising flow is controlled. It suggests that the heat rising flow of two building fire behind the building at the leeward is stronger than those of one building fire.

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In this report, the authors tried to develop the physical model of scattering firebrands that is one of the propagation factors of urban fire propagation and simulate the scattering firebrands by means of CFD with a turbulence model. Actually, the shape of firebrands are various and the big firebrands have capacity of fire propagation. In this case to predict urban fire spreading correctly, using Lagrange equation that considered gravity and drag is desirable to simulate the each of firebrands scattering. In this report the authors assumed that firebrands are sphere, and analyzed scattering by using CFD.

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Firebrands and spot-fires caused by them are the important factors in case of an urban fire. However, only a few engineering approaches have been done for research of firebrands due to a lack of appropriate experimental facilities. Therefore, the authors implemented a fullscale fire-test in the Fire-Wind-Tunnel to bum a fire-preventive wooden house and tried to find out how firebrands generated during the fire. And the main purpose was to quantitatively as well as qualitatively understand the correlation between the generation of firebrands and the progress of a fire. Conclusions are as follows: (1) Phenomena during a fire, which greatly generate firebrands, are flashover, collapse of framework-members, opening jet plume, and so on. (2) Firebrands generated from a burning house were collected and the mass of each firebrand was measured. (3) The authors will implement other fullscale fire-tests using Fire-Wind-Tunnel with different experimental conditions such as wind velocity and a structural type of a house.

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Scatter of firebrands caused by a fire is numerically simulated by means of CFD (Computational Fluid Dynamics) based on a turbulent model. The results are compared with an investigation by the authors on the distribution of firebrands and spot fires due to a hotel fire occurred in Shirahama, Wakayama prefecture on November 17th 1998 by exploration and questionnaire. New Technique concerning motion of a flying firebrand is included in the model, and scatter of them can be predicted realistically in comparison with the former method by the authors.

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Scatter of firebrands caused by a fire is numerically simulated by means of CFD (Computational Fluid Dynamics) based on a turbulent model. The results are compared with an investigation by the authors on the distribution of firebrands and spot fires due to a hotel fire occurred in Shirahama, Wakayama prefecture on November 17th 1998 by exploration and questionnaire. New Technique concerning motion of a flying firebrand is included in the model, and scatter of them can be predicted realistically in comparison with the former method by the authors.

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Airflows over steep complex terrain with characteristic length scales of the order of kilometers contain the flow impingement, separation and reattachment. In order to develop an accurate model of simulating the above-mentioned topographic effects, we have been examining the large-eddy simulation(LES) technique using a finite-difference method(FDM). These LES codes are referred to as the RIAM-COMPACT(Research Institute for Applied Mechanics, Kyushu University, Computational Prediction of Airflow over Complex Terrain). In the present study, we tried to the calculation considering the meso-scale meteorological field obtained from CSU-RAMS(Colorado State University, Regional Atmospheric Modeling System).

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New wind climate assesment method, Dynamical-Statistical Downscaling Method was proposed. Followng results were obtained. 1)With regional atmospheric model, prediction of regional wind climate, which includes the effect of large scale terrain and atmospheric stability, was made possible. 2)Proposed method enables the precise wind climate assesment at any point without observation.

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Idealiaing and realizing approach was proposed. Regional atmospheric and local wind prediction model MASCOT was used to estimate local wind climate at Tappi Promontory. Following results were obtained. 1)This approach enables the wind climate assesment without observation; 2)This approach can predict the annual mean wind speed with the error of about 8 percent.

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WAsP is a computer program which is originally developed in Denmark and have been applied in many wind turbine sites in the world. Since in japan in general wind farm sites are located in complex topographies, its applicability to those complex terrain has been a controversial issue. MASCOT is a computer program which implemented the k-epsilon turbulense model. Its applicability was verified on wind tunnel experiment and a Tappi Wind Park. In this paper a comparison of wind power production is made between those programs.

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The usage of soft energy has drawn public attention increasingly. The wind-energy which produced around buildings in urban area is predicted by numerical flow computation (CFD).

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Wind tunnel experiments were carried out to measure performance characteristics and to observe the flow patterns of rotating blades in a small scale wind turbine. Visualization of the blade surface flow patterns was achieved using two well known techniques of the oil-film flow visualization method and the tufts. Two different airfoils were studied the Clark Y and the MEL002. For the Clark Y airfoil tests were performed for tripped and untripped conditions, for the MEL002 airfoils just untripped conditions were studied. Comparisons of the performance characteristics for the tripped and the untripped tests conditions, for the Clark Y airfoil, showed little improvement in efficiency. In the case of the MEL002 airfoil two peak values of power coefficient were measured at a wind speed of 8 m/s. Tip speed ratio variation influenced the boundary layer behavior. Complex flow patterns on the rotating blades surface were confirmed by the visualization methods and identified. The flow visualization allowed the identification of laminar flow, laminar separation bubble formation, flow reattachment, turbulent boundary layer, and turbulent separation.

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In the method of Murakami et al. used as one of the wind environment assessment, the day maximum gust velocity which is an evaluation measure is converted into the day maximum average velocity by a gust factor. However, the assessment results are change greatly by the way of taking this gust factor, therefore, it is hoping for the proposal of the method which gives the gust factor appropriately.This research proposed an expression which gives the gust factor, based on full-scale measurements of wind velocity and examined about that validity.

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This study investigates the modeling for the effects of tree on wind flow. Previous researches on plant canopy models are reviewed and optimized. Accuracy of the two types of plant canopy models optimized here is confirmed by comparing its results with field measurement. Special attention is paid for the appropriate value of the model coefficients in this study.

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Various scenarios on urban planning have been proposed to minimize the impacts of urbanization on urban climate. Among them, replanting at the urbanized area such as roof planting is the most popular measure used, and major cities have actually introduced programs to promote the urban tree planting. The method of tree planting surely decreases air temperature, but an increase in air humidity has subsequently occurred. Thus, these two aspects should be considered simultaneously in order to evaluate the effects of urban planting. A new concept for evaluating the countermeasure for heat island, which considers the generation and transports of sensible heat and latent heat, is proposed as "Urban Thermal Metabolism model". The impact of urban tree planting on urban climate in Tokyo is quantitatively evaluated based on this model.

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In this paper, it is described that air temperatures were observed to confirm
the urban heat island phenomena and the
influence of the sea breeze was
analyzed at summer season in
Sendai city area. Observation was
set up about 30-38
observing points. Each of thermometers
was set up in the meteorological
monitoring shelter at the playground
of an elementally school.
As the results, following items were
mentions. Temperature difference
between the city center and
the suburbs was about 5
centigrade in daytime and about
2 centigrade before daybreak. It was
clarified the regional characteristics
of air temperatures distribution.
As the influence of sea breeze ,
its sphere was about 10-15km from
the observed point near the sea shore.

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The deterioration of the outdoor thermal environment in summer is pointed out, and the effectiveness of the use of the sea breeze is paid to attention as one of the measures in not only the conurbation but also the local city in recent years. In this research, a long-term measurement was done for the Haramachi City located in the Pacific Ocean coast in the Tohoku region aiming to obtain the data of a typical fine day in summer. Consequently, the tendency that the temperature rises was seen on the day where the sea breeze did not blow, and the tendency to which the temperature greatly decreased was seen on the day where the sea breeze blew. The heat mitigation effect of the sea breeze was confirmed from these results.

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Wind tunnel experiment was performed on concentration fluctuation of short timely released tracer gas in atmospheric boundary layer. Concentration fluctuation was measured by the fast response flame ionization detector and mean concentration and the instantaneous high concentration value were evaluated. Ensemble mean concentration of short timely released (Cflat) and time average concentration of continuous release (Cmean) showed similar features. Concentration ratio of maximum 1%value (c99) of short timely released showed larger scatter than those of the continuous released. Furthermore, the probability density function of c99 showed almost the same profiles of lognormal distribution on a gas center axis, viz., plume center position, and the exponential distribution at plume edge position, and gumbel distribution at both measuring positions.

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Inside-and-outside airflow for buildings is complex a phenomenon complicated with turbulence behavior. Therefore a wind environment around a building is significant. Especially in Japan, there are many kinds of ups-and-downs. It is so important to consider both building arrays and ground undulation for assessment of airflow. But at present there are few studies to discuss these effects. In this research, we try to provide LES model for wind flow in actual suburban area by using the GIS data, which represent details of the ground surface consisting of houses and vegetation. So Yokohama area is treated as numerical example and LES computation is carried out by using nested grid. We clarify the characteristics of inside-and-outside airflow for building model located in actual urban area.

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The purpose of this study is to examine the accuracy of CFD prediction of flow around a high-rise building including the velocity distribution at pedestrian level. This paper reports the cross comparison of CFD results of flow around building model by various RANS models, i.e., the standard k-eps model, revised k-eps models in order to clarify the major factors which affect prediction accuracy.

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The working group planed to carry out the cross comparison of CFD results of flow around building model with shape by various k-e turbulence models in order to investigate the performance of revised k-e turbulence models in the same condition. Results of the analyses were compared with experimental data. The standard k-e model overestimated turbulent energy in flow with Impinging. This drawback was corrected by all revised k-e models tested here. But revised k-e models overestimated the reattachment length behind the building in comparison with the standard k-e model.

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We measured the wind velocity ratio in the street around a central building block of nine building blocks.The result is shown below.(1)The wind velocity ratio in the street in 45 degrees of wind directions becomes high compared with 0 degree of wind directions.(2)In the lee side of a central building, since the direction of a wind flows is changing to the right direction and the opposite direction, the measurement value by the thermistor anemometer is high a little.

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At part4, we carry out the cross comparison of CFD results of flow around building blocks by various numerical methods, in order to clarify the major factors which affect prediction accuracy.

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Time-depending air flows around a 4:4:1 square cylinder are simulated with LES. The obtained time-averaged velocity distributions show good accordance with wind-tunnel experiments. It is also shown that time-averaged scalar velocity distributions can be reproducedwith using the magnitude of time-averaged velocity vector and fluctuating velocity.

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We made a PC cluster and performed benchmark tests with CFD code. The speed up ratio of the PC cluster depends on the performance of network used and number of grids computed. Gigabit Ethernet has a good cost performance. A simple equation proposed for predicting speed up ratio shows good agreement with experiments.

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The New type of actively controlled Multiple-Fan type wind tunnels have been developed in our laboratory, to simulate a atmospheric boundary layer flow. The time variable revolution of each fan is controlled independently by a computer. In this report, controlled fluctuating air-flow in this wind tunnel was analyzed by Auto-correlation method. The large integral scale of turbulent vortex was generated highly reproducibility. In this conclusion, low frequency response of active controlled air-flow was highly reproducibility in this wind tunnel.

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Three basic driving methods for a multi-fan type wind tunnel were taken and compared with each other. The structure of turbulent flow due to a partially-active method is as follows: Immediately past the outlet of the contraction, tubulence is generated due to the instability of shear flow, so that the pulsating and naturally stirred-up component coexists. The stirred-up component decays quickly as it travels downstream, but the pulsating component survives farther downstream.

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In an attempt to generate strong turbulence within a limited entry length, an innovative multi-fan type has been developed. The airflow is driven by an array of fans, each of which is independently controlled by a computer.
In this study, each of fans are driven by signals with randomly distributed phases and statistical turbulent parameters are investigated.

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In this study, an new active turbulence generator, which can control the spatial correlation of the vertical component of fluctuating velocity, was developed. It was indicated that this turbulence generator made some turbulent flows, which had some different integration scale along span-wise axis and the same power spectrum, by giving the difference of the phase between the motor controlling signal. Moreover, the gust response of 3D model with a flat rectangular cross-section was investigated in the generated turbulence flow. It was indicated that the gust response amplitude in 3D turbulent flow decreased in comparison with that in 2D turbulent flow.

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Placing vertical plates in the windward part of the working section and oscillating them by a motor, we have tried to generate direction-changing flow in a wind tunnel. The lateral component of the flow fluctuates with frequency which is equal to the oscillation frequency of the plate. However, the longitudinal component fluctuates with frequency which is either equal to or two times the oscillation frequency.

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This system has two large permanent magnets on the top and under the bottom of the measurement cross section. The gravitational force applied on the model is suspended by the magnetic force produced by these two magnets. Hence, the electric power under the operation without aerodynamic force can be decreased as small as zero level.

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