著者

横山 広樹 大岡 龍三 菊本 英紀

出版者

日本建築学会

雑誌

日本建築学会環境系論文集 (ISSN:13480685)

巻号頁・発行日

vol.82, no.738, pp.767-777, 2017 (Released:2017-08-30)

参考文献数

31

被引用文献数

1

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Urban environmental issues related to heat and aerial pollutants have become increasingly more serious. Atmospheric properties, such as air temperature, wind velocity, and pollutant concentrations, are typically measured at meteorological observation stations. However, due to the low spatial resolution of the station networks, we cannot observe local issues occurring on the scale of people's daily lives. Thus, mobile measurement is an effective method for addressing the insufficient measurement points in urban areas. However, the extent of Global Positioning System (GPS) measurement errors are unclear and results of mobile measurements are uncertain. Therefore, this paper discusses the applicability of mobile measurements to high-density urban areas. After investigating the range of GPS errors, we consider the following three aspects: (1) spatial distribution of air temperature at a high spatial resolution of 10 m; (2) the range of uncertainties in mobile measurement results; and (3) the impact of spatial resolution (10 m or 100 m) on the measured spatial distribution of air temperature. In this study, we used bicycles as mobile measurement platforms to investigate the spatial distribution of air temperature. Two measurement sites in Tokyo were selected: Shinjuku, a commercial area (August 25th to 28th, 2015) and Shibuya, a residential area (January 20th to 29th and February 16th to 19th, 2016). We equipped bicycles with platinum resistance thermometers (a high responsivity rate of 2.2 s), a data logger, and a GPS logger to measure air temperature and spatial position during the sequential travel of the bicycles. Measurements in Shinjuku were conducted on cloudy days. To ensure that the measurement conditions were consistent, measurements in Shibuya were conducted from 16:00 to 18:00, when solar radiation, and thus its influence, was very low. From the results, we draw the following conclusions. Firstly, GPS data collected in urban areas tend to include positioning errors of 14 m on average due to the reflective properties of building surfaces according to adapting our developing correction method. Secondly, spatial distribution of air temperature variation was almost ±0.65 °C (min to max). Thirdly, the average of uncertainty of air temperature variation was 0.03 °C. It was much smaller than the range of air temperature variation (min to max). Lastly, we can find a similar distribution of air temperature between a mesh size of 10 m and 100 m. However, a spatial resolution of less than 100 m was necessary in order to observe locations where the air temperature is locally higher than near street intersections. However, we have to consider GPS errors are 14 m on average, which is larger than a mesh size of 10 m. From the above, we obtained a characteristic spatial distribution of air temperature by correcting position data. Suppose that we reduce uncertainty to less than 0.1 °C in the case that the max value of standard deviation of air temperature at each cell is 0.4 °C, 16 samples at each cell must be corrected in one hour. Therefore, we found mobile measurement is an effective method for investigating environmental conditions in high-density urban areas for high spatial resolution.

著者

菊本 英紀 陳 然

出版者

東京大学生産技術研究所

雑誌

生産研究 (ISSN:0037105X)

巻号頁・発行日

vol.75, no.1, pp.45-52, 2023-02-01 (Released:2023-02-23)

参考文献数

11

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室内空間の気流特性を考慮し空気清浄機の効果を評価するため,CFD を用いた空気清浄機吹出気流の空気齢および吸込気流の空気余命に関する解析手法を提案した.また本手法を用いて,可搬型の空気清浄機が設置された室内空間を対象とした解析を実施した.その結果,換気と分離して空気清浄機のみの空気齢や空気余命の空間分布を解析できることを示した.本手法により,単なる汚染質濃度の低減効果だけでなく,非定常かつ突発的な汚染質発生などに対して,空気清浄機がいかに迅速に汚染質を除去し,清浄な空気を届けられるかという時間的観点からも評価が可能となる.

著者

菊本 英紀 大岡 龍三

出版者

日本建築学会

雑誌

日本建築学会環境系論文集 (ISSN:13480685)

巻号頁・発行日

vol.87, no.801, pp.759-765, 2022-11-01 (Released:2022-11-01)

参考文献数

23

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Based on the assumption of a non-uniform pollutant concentration distribution and stochastic determination of pollutant sources and receptors in indoor space, this study shows how to formulate the expected pollutant concentration observed by the receptors in the presence of an air cleaner, using adjoint concentration and parameters related to probability of pollutants passing through the cleaner. Using this formulation, the structure of the concentration reduction effect of the cleaner and its optimal placement are discussed. The studies with the formulation are also conducted under the assumption of instantaneous uniform diffusion and for a problem in one-dimensional space.

著者

張 秉超 大岡 龍三 菊本 英紀

出版者

一般社団法人 日本風工学会

雑誌

風工学シンポジウム講演梗概集 (ISSN:24354392)

巻号頁・発行日

pp.51-56, 2020 (Released:2021-05-25)

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本研究では、単体角柱建物モデル周りの乱流のモード解析の結果に基づいて、カルマン渦の動的システム同定を行った。まず、乱流速度データに対して固有直交分解を実行した。その結果、モード2は流入変動によって制御され、モード1、3、4は主な周期的なカルマン渦を表した。次に、モード1、3、4の動的システムを多項式回帰モデルにフィットし、状態の軌跡の平均的な傾向を解明した。回帰モデルの2つのリミットサイクルは、システムに摂動がない場合の最終状態として渦の2つの回転方向を表した。さらに、回帰モデルから生成された軌跡から2つの特徴的な周期が識別され、渦の速い運動と遅い運動と2つの運動パターンがあることを示した。

著者

有馬 雄祐 大岡 龍三 菊本 英紀

出版者

日本建築学会

雑誌

日本建築学会環境系論文集 (ISSN:13480685)

巻号頁・発行日

vol.81, no.729, pp.1047-1054, 2016 (Released:2016-11-30)

参考文献数

21

被引用文献数

2

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The outputs of weather and climate models have been used in various application fields. For example, future weather data for the building energy simulation (BES) can be provided based on a climate model prediction. However, as the model output has systematical errors (called the bias), some type of bias correction is necessary in order to use the model output for an application field. For temperature or humidity, we often assume normal distribution and correct bias using statistical parameters, such as the average and the standard deviation. However, for solar radiation, a bias correction method (BCM) that uses only the average and standard deviation is insufficient and can result in negative values after bias correction. Consequently, the solar radiation bias is often corrected using only its average. In general, climate models can accurately predict the daily maximum amount of solar radiation on clear days at a given site because solar radiation depends mainly on its geolocation (latitude, longitude, and elevation) and the season (solar altitude). However, it is difficult to model cloud physics processes accurately to establish the weaker amounts of solar radiation on cloudy days. As a result, when we correct the solar radiation bias using only the average value, the daily maximum value deviates from the observed results instead of correcting the average. In this paper, we present a method called quantile mapping (QM) for the bias correction of solar radiation to provide the bias corrected weather data for the BES. The QM has been developed mainly for the correction of precipitation or temperature biases, although there are few studies that apply QM to the correction of solar radiation. In previous studies, QM was applied to the daily or monthly average. However, for the BES, the daily maximum value is also as important as the daily or monthly average, because the peak energy load depends mainly on the daily maximum. In this study, we also applied QM to obtain the daily maximum amount of solar radiation. In addition, we conducted BESs using the bias corrected weather data and evaluated the efficiency of each BCM. From the simulation results, the average energy consumption did not differ according to the difference in the BCM. However, the simulation that used the weather data corrected by only the monthly average could not predict the maximum cooling load; it was underestimated by 12%. Conversely, the simulation with the data corrected by QM, which used either the daily cumulative or the maximum amount of solar radiation, could predict the maximum cooling loads, which were under estimated by only 6% and 2%, respectively.

著者

菊本 英紀

出版者

一般社団法人 日本風工学会

雑誌

風工学研究論文集 (ISSN:24354384)

巻号頁・発行日

vol.26, pp.148-156, 2020 (Released:2021-05-25)

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本研究では、k-εモデルおよび濃度輸送方程式を用いたCFD解析により点源発生の汚染物質拡散を予測するため、トラベルタイムを利用した乱流拡散係数リミッタを提案した。同手法では、トラベルタイムも放射性トレーサーと呼ぶ仮想トレーサーにより数値的に予測される。また、同手法を2次元一様乱流場における点源発生の汚染物質拡散予測に適用し、理論的に予測される拡散初期のトラベルタイムに比例した拡散幅の増加挙動を再現できることを示した。また、乱流拡散係数リミッタに含まれる3つのモデル変数の調整により、拡散初期および終期の乱流拡散係数および拡散幅を制御できることを示した。

著者

大風 翼 菊本 英紀 小野 浩己 今野 雅 池谷 直樹 挾間 貴雅 中尾 圭佑 岸田 岳士 田畑 侑一 中島 慶悟 義江 龍一郎 富永 禎秀

出版者

一般社団法人 日本建築学会

雑誌

日本建築学会技術報告集 (ISSN:13419463)

巻号頁・発行日

vol.26, no.62, pp.179-184, 2020-02-20 (Released:2020-02-20)

参考文献数

20

被引用文献数

6

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Appropriate large-eddy simulation (LES) guidelines for pedestrian wind environments are being established by the working group of the Architectural Institute of Japan. We conducted LESs for a flow field around an isolated building to clarify the influence of computational conditions on turbulent statistics. We performed a cross-comparison study by examining both experimental and LES results for various computational conditions such as grid arrangements, subgrid scale models, spatial derivation schemes for convection term, and convergence criterion for a coupling algorithm of flow and pressure fields. Results can be used to provide LES guidelines for predicting the pedestrian wind environment.

著者

有馬 雄祐 大岡 龍三 菊本 英紀 山中 徹

出版者

東京大学生産技術研究所

雑誌

生産研究 (ISSN:0037105X)

巻号頁・発行日

vol.66, no.1, pp.61-68, 2014-01-01 (Released:2014-03-18)

参考文献数

21

被引用文献数

1

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地球温暖化など気候変動が進んでおり,建築は気候から多大な影響を受ける.気候に適した設計を行うために,気温や日射などの気象要素から成る標準気象データを用いた熱負荷計算が行われる.現在は,各地域の過去の観測値を基にして作成された標準気象データを使用することが一般的である.しかし,建築物は長期にわたり使用され,その間に気候は変動する.そのため,将来の気候へ適応した,長期的な省エネを実現する建築設計のためには気候変動を考慮した熱負荷計算が必要である.そこで本研究では,GCMの予測する気象データを領域気象モデルによって力学的ダウンスケーリングを行い未来の標準気象データの作成する.

著者

中島 慶悟 大岡 龍三 菊本 英紀

出版者

一般社団法人 日本風工学会

雑誌

日本風工学会論文集 (ISSN:13493507)

巻号頁・発行日

vol.42, no.1, pp.9-21, 2017-01-31 (Released:2017-05-15)

参考文献数

18

被引用文献数

1

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Computational fluid dynamics (CFD) analysis using large-eddy simulation (LES) and standard k-ε model (k-ε) was conducted for flow within and above urban canyon under various conditions of thermal stratification. The results of LES and k-ε were compared with the wind tunnel experiment to investigate the prediction accuracy of CFD analysis. k-ε failed to reproduce the spatial distribution of the mean wind velocity vector and mean temperature within the urban canyon compared with LES in unstable case. k-ε underestimated the Reynolds stress <u1’u3’> and turbulent heat flux <u3’T’> within the urban canyon in unstable case. It is thought that the prediction accuracy of k-ε decreases because k-ε underestimates the exchange of momentum and heat within and above the urban canyon compared with LES and the wind tunnel experiment.

著者

菊本 英紀 崔 元 準 大岡 龍三

出版者

日本建築学会

雑誌

日本建築学会環境系論文集 (ISSN:13480685)

巻号頁・発行日

vol.82, no.734, pp.357-365, 2017 (Released:2017-04-30)

参考文献数

23

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Natural ventilation is a good measure to reduce the thermal load of a building and create a good thermal environment for the occupants. To predict the ventilation performance of a building, related ventilation parameters should be estimated. However, obtaining an accurate prediction or estimation before the construction is completed is difficult because of the fluctuating characteristics of turbulent, complex local flow field affected by surrounding buildings and city-scale topology. These problems make the application of natural ventilation difficult, and therefore, an in situ experimental method adopted after the construction of a building is completed would be a more reliable way of obtaining accurate ventilation parameters. The tracer gas method is a frequently used in situ method to examine ventilation performance. However, deterministic evaluation using this method has its drawbacks in terms of accuracy, and the uncertainty of results could be large because of fluctuating environmental conditions and intrinsic error of measurement. Therefore, when parameters related to natural ventilation are estimated, the estimates and their uncertainty should be concurrently evaluated. In this study, using a Bayesian approach, we propose a new estimation method that yields not only the estimates, but also the probability distribution of the estimates. To validate the proposed method, we reproduced a tracer gas experiment using computational fluid dynamics (CFD) simulation because the experimental absolute true values that are unknown in most situations were required for evaluating the proposed method. Using the data from CFD simulation, estimations of the ventilation rate and effective room volume were obtained using two different methods: probabilistic estimation based on Bayes' theorem, and deterministic estimation using the quasi-Newton method. In the probabilistic estimation, a method of simultaneously estimating the degree of the difference between the measurement value and the prediction value required for estimation was proposed. The estimation results showed that the estimated values of the deterministic method and probabilistic method (mode of probability distribution function) were very close to the true value set in the CFD simulation. However, the probabilistic method has some advantages over the deterministic method in that the former method can provide not only the estimates, but also the probability distribution of each estimate and its confidence interval. Additionally, in the case of a simultaneous estimation of more than two unknown parameters, it is important to analyze the correlation among parameters. By creating a joint probability density function, the correlation between the estimation parameters is determined, and this is another important advantage of the probabilistic estimation method.

著者

菊本 英紀 大岡 龍三

出版者

日本建築学会

雑誌

日本建築学会環境系論文集 (ISSN:13480685)

巻号頁・発行日

vol.81, no.730, pp.1127-1136, 2016 (Released:2016-12-30)

参考文献数

33

被引用文献数

1

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Particulate matter (PM) adversely affects human health. Even though PM tends to consist of higher concentrations outdoors, indoor PM concentrations should not be overlooked, given that people spend most of their time indoors. When there is no strong indoor PM source, indoor concentrations change within a certain ratio following the diffusion of outdoor concentrations indoors. The Indoor/Outdoor (I/O) concentration ratio is affected by static building properties such as airtightness, ventilation system type, and the system's air filter performance. However, natural ventilation can have a dynamic influence on the I/O ratio because of significant changes in ventilation rates and flow patterns within the building. This study measured PM concentrations for particles ranging from 0.3 to 10 μm in size. The study was conducted in a room of an office building in Tokyo, over a three-week period. The size ranges were divided into 16 channels and 10-min averages of the number of particles at each channel were measured using an optical particle counter. Occupants in the room utilized natural ventilation by manually opening a window. The window was opened and closed twelve times during the entirety of the measurements. Because outdoor PM consisted of higher concentrations than that found indoors, the natural ventilation lead to larger Indoor/Outdoor (I/O) concentration ratios. The PM concentrations were observed to increase and decrease just after the window was opened and closed, respectively. These concentration changes were more remarkable for PM consisting of larger particle sizes. Where PM measured 10 μm, concentrations increased 8 times after opening the window and decreased 0.5 times after closing the window on an average hourly basis. Particle-size is a factor for concentration changes caused by natural ventilation as discussed using concentration prediction based on the mass balance equation of indoor PM. As a result, the dependency was explained quantitatively in terms of the difference in the gravity-settlement velocity of the particles. Using ventilation parameters estimated in this analysis, the I/O ratio of PM concentration as a function of the particle size was predicted. During natural ventilation, indoor PM consisting of particles smaller than 1 μm can have the equivalent concentration of outdoor PM. However, particle size increase leads to a larger gravity-settlement velocity and lower I/O ratio. Therefore, particles measuring 10 μm are predicted to have an I/O ratio of 40% in accordance with the room analyzed in this study.

著者

菊本 英紀 大岡 龍三 加藤 信介

出版者

日本建築学会

雑誌

日本建築学会環境系論文集 (ISSN:13480685)

巻号頁・発行日

vol.81, no.725, pp.607-614, 2016 (Released:2016-07-30)

参考文献数

21

被引用文献数

2

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When the concentration of an aerial pollutant is detected at some observation points in an urban or built environment, immediate source identification allows for application of effective measures to decrease the concentration of the pollutant and its adverse effects. In this case, source identification involves determination of the source position and source strength from measured concentrations. We propose a novel method for identifying the source of an environmental pollutant continuously released from a point source in a turbulent flow field at a statistically steady state. The method employs the analysis of tracer dispersion released from observation points of the pollutant in a reversed flow field (RFF). The RFF is artificially produced from the forward flow field (FFF) in which the pollutant is transported. The direction of temporal progress and velocity vectors in the RFF are created opposite to those in the FFF. In a statistically steady turbulent flow and concentration field, the concentration of matter at a position can be expressed as a product of its source strength and expected staying time (EST) per unit volume at the position of a particle of the matter. From the discussion on the probabilistic behavior of a virtual particle in the flow fields, we found that the EST between two related points has an identical value when the release and monitoring points are interchanged in the FFF and RFF. Using the relationship of the EST and the tracer dispersion from the observation points in the RFF, the measured concentration of the pollutant and the EST give the estimated source strength as a function of the position. This property coincides with the duality of the scalar fields analytically derived in the adjoint method. When they have multiple observation points, each tracer dispersion analysis gives different distributions of the estimated source strength. However, the source strength has to have a unique point value for physical realizability. This condition reduces candidate positions of the pollutant source. When the dispersion of the pollutant occurs in the n-th dimensional space, the number of parameters is n + 1, which contains n space coordinates of the source position and the source strength. Consequently, n + one observation points allow the determination of all parameters in the source identification. This paper presents the basic idea of the source identification method based on physical consideration of the particle behavior in the RFF. An example of the source identification procedure is also presented for pollutant dispersion in a two-dimensional uniform flow field. However, the solution of source identification obtained with the present method can be very sensitive to the errors that are assumed to occur in the measurement or analysis of flow and concentration fields. For practical applications, an additional method to provide robust solutions against these errors are needed and will be considered in future studies.

著者

富永 禎秀 大風 翼 菊本 英紀 白澤 多一 義江 龍一郎 持田 灯

出版者

日本建築学会

雑誌

日本建築学会技術報告集 (ISSN:13419463)

巻号頁・発行日

vol.22, no.51, pp.609-614, 2016 (Released:2016-06-20)

参考文献数

10

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Recently, applications of CFD (Computational Fluid Dynamics) are expanding to various environmental issues such as pollutant/thermal dispersion in urban areas. The outdoor environment sub-committee of the Architectural Institute of Japan have conducted several benchmark tests for obtaining basic information and knowledge in order to provide the extended practical guidelines of CFD, which can be applied to more broad environmental issues than the present ones. This paper reports the results which considered the sensitivity of various computational conditions in the RANS (Reynolds-Averaged Navier-Stokes equations) model to the prediction accuracy of pollutant concentration distributions for two different configurations.