KINDAI UNIVERSITY


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MICHIOKA Takenobu

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FacultyDepartment of Mechanical Engineering / Graduate School of Science and Engineering Research
PositionAssociate Professor
Degree
Commentator Guidehttps://www.kindai.ac.jp/meikan/1372-michioka-takenobu.html
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Last Updated :2020/04/03

Education and Career

Education

  •   1993 04  - 1996 03 , Kyushu University, School of Engineering

Academic & Professional Experience

  •   2015 04 ,  - 現在, Faculty of Science and Engineering, Department of Mechanical Engineering, Kindai University
  •   2001 04 ,  - 2015 03 , Central Research Institute of Electric Power Industry
  •   2012 04 ,  - 2013 03 , School of Engineering, Kyushu University

Research Activities

Research Areas

  • Social infrastructure (civil Engineering, architecture, disaster prevention), Construction environment and equipment
  • Manufacturing technology (mechanical, electrical/electronic, chemical engineering), Fluid engineering

Published Papers

  • Large‐eddy simulation for atmospheric dispersion of stack gas with momentum plume‐rise and building downwash, 瀧本浩史, 小野浩己, 佐藤歩, 道岡武信, 日本風工学会論文集, 日本風工学会論文集, 44(3), 59‐67, Jul. 31 2019
  • Effect of Ships on Wind Flow in Ocean Wind Measurements Using a Numerical Simulation, Suzuki Naoya, Michioka Takenobu, Konda Masanori, Kutsuwada Kunio, Masuda Yuji, Journal of Advanced Marine Science and Technology Society, Journal of Advanced Marine Science and Technology Society, 25(1), 1 - 14, 2019
    Summary:<p>Generally, the air-sea momentum, heat, and CO<sub>2</sub> gas flux are calculated in field observation using the eddy correlation method, which simultaneously measures the horizontal and vertical wind components. Measuring the components of wind velocity is usually limited to fixed installations owing to the minor effect of the platform on the wind flow. Occasionally, numerical simulations are sometimes used for shipboard observations. However, the details of the effect of the wind flow around an observation ship are scarcely investigated using numerical simulations, although ships affect the wind flow and wind direction by wind distortion. In this study, we investigated the effect of ships on the wind flow around the Hakuho–Maru of the Japan Agency for Marine-Earth Science and Technology using a numerical simulation. As a result of the flow visualization, measuring the horizontal and vertical components of wind velocity was very difficult because the wind distortion (upward and downward gusts, among others) was very large owing to the effect of the ship. This showed that the effect of the ship was significant for the measurements of air-sea momentum, heat, and CO<sub>2</sub> gas flux.</p>
  • Large-Eddy Simulation of the Effects of Wind-Direction Fluctuations on Turbulent Flow and Gas Dispersion Within a Cubical Canopy, Takenobu Michioka, Hiroshi Takimoto, Hiroki Ono, Ayumu Sato, Boundary-Layer Meteorology, Boundary-Layer Meteorology, Jan. 01 2019
    Summary:© 2019, Springer Nature B.V. Large-eddy simulation of turbulent flow and gas dispersion in a cubical canopy is used to investigate the effect of wind-direction fluctuations on gas dispersion. Square blocks are set at regular intervals on the bottom surface, with line sources placed within the first, second, third, fifth and seventh rows. Large-eddy simulation without wind-direction fluctuations produces a good prediction of the mean streamwise velocity component, and the standard deviations of the fluctuations in the streamwise and spanwise velocity components, obtained from a wind-tunnel experiment. Wind-direction fluctuations marginally affect the mean streamwise velocity component above the canopy in the first row, and do not significantly affect the component beyond the third row. The standard deviations of the fluctuations in the streamwise and spanwise velocity components above the canopy are also affected by wind-direction fluctuations, but within the canopy the components are less sensitive to the fluctuations beyond the third row. The spatially-averaged concentrations within the canyon with wind-direction fluctuations before the third row are marginally greater than concentrations without the fluctuations, but they are essentially identical beyond the fifth row. The low-frequency turbulent flow that passes through the canyon is generated with and without wind-direction fluctuations.
  • Large-eddy simulation for turbulent flow and gas dispersion over wavy walls, Takenobu Michioka, International Journal of Heat and Mass Transfer, International Journal of Heat and Mass Transfer, 125, 569 - 579, Oct. 01 2018
    Summary:© 2018 Elsevier Ltd Large-eddy simulation is implemented for turbulent flow and gas dispersion over wavy walls across a wide range of the wave amplitude to wavelength ratio (α = 1.0, 1.5, and 2.0). Two tracer gases are emitted from point sources located at a single crest and trough of the wavy wall. Because the values of α increase under the Reynolds number based on the bulk velocity and the wavelength is 6.67×104, the flow separates behind the crest and the standard deviations of the fluctuation in streamwise and spanwise velocity components become relatively large especially at the upslope of the wavy wall. The increase are related to the vortices linked to the Görtler instability mechanism. The change in the flow pattern with respect to the value of α significantly affects the gas dispersion within the valley. As the Reynolds number increases under the wavy wall with α = 2.0, the flow tends to follow the bottom surface of the wavy wall and the number of the vortices increases at the upslope, but the vortices do not significantly affect the gas dispersion over the wavy wall.
  • Effects of Fetch on Turbulent Flow and Pollutant Dispersion Within a Cubical Canopy, Takenobu Michioka, Hiroshi Takimoto, Hiroki Ono, Ayumu Sato, Boundary-Layer Meteorology, Boundary-Layer Meteorology, 168, 247 - 267, Aug. 01 2018
    Summary:© 2018, Springer Science+Business Media B.V., part of Springer Nature. The effects of fetch on turbulent flow and pollutant dispersion within a canopy formed by regularly-spaced cubical objects is investigated using large-eddy simulation. Six tracer gases are simultaneously released from a ground-level continuous pollutant line source placed parallel to the spanwise axis at the first, second, third, fifth, seventh and tenth rows. Beyond the seventh row, the standard deviations of the fluctuations in the velocity components and the Reynolds shear stresses reach nearly equivalent states. Low-frequency turbulent flow is generated near the bottom surface around the first row and develops as the fetch increases. The turbulent flow eventually passes through the canopy at a near-constant interval. The mean concentration within the canopy reaches a near-constant value beyond the seventh row. In the first and second rows, narrow coherent structures frequently affect the pollutant escape from the top of the canopy. These structures increase in width as the fetch increases, and they mainly affect the removal of pollutants from the canopy.
  • Numerical simulations of dry and wet deposition over simplified terrains, T. Michioka, T. Michioka, H. Takimoto, H. Ono, A. Sato, Asian Journal of Atmospheric Environment, Asian Journal of Atmospheric Environment, 11, 270 - 282, Dec. 01 2017
    Summary:To evaluate the deposition amount on a ground surface, mesoscale numerical models coupled with atmospheric chemistry are widely used for larger horizontal domains ranging from a few to several hundreds of kilometers; however, these models are rarely applied to high-resolution simulations. In this study, the performance of a dry and wet deposition model is investigated to estimate the amount of deposition via computational fluid dynamics (CFD) models with high grid resolution. Reynolds-averaged Navier-Stokes (RANS) simulations are implemented for a cone and a two-dimensional ridge to estimate the dry deposition rate, and a constant deposition velocity is used to obtain the dry deposition flux. The results show that the dry deposition rate of RANS generally corresponds to that observed in wind-tunnel experiments. For the wet deposition model, the transport equation of a new scalar concentration scavenged by rain droplets is developed and used instead of the scalar concentration scavenged by raindrops falling to the ground surface just below the scavenging point, which is normally used in mesoscale numerical models. A sensitivity analysis of the proposed wet deposition procedure is implemented. The result indicates the applicability of RANS for high-resolution grids considering the effect of terrains on the wet deposition.
  • Development of a Numerical Model for Predicting the Atmospheric Dispersion of Hydrogen-Sulfide Emitted from Goethermal Power Plants, 小野浩己, 瀧本浩史, 佐藤歩, 道岡武信, 道岡武信, 佐田幸一, 大気環境学会誌, 大気環境学会誌, 52(1), 19‐29, Jan. 10 2017
  • Effect of Observation Tower on Wind Flow over the Ocean-First Assessment of the Applicability of Numerical Simulation Using CFD-, 鈴木直弥, 早稲田卓爾, 道岡武信, 辰巳公亮, 竹本剛志, 海洋理工学会誌(Web), 海洋理工学会誌(Web), 23(1), 11‐19(J‐STAGE), 2017
  • Large Eddy Simulation of Atmospheric Dispersion of Cooling-tower Exhaust over a Simple Shaped Hill-Validation of Flow and Dispersion Field with Different Shaped Grids-, 小野浩己, 瀧本浩史, 道岡武信, 佐藤歩, 佐田幸一, 大気環境学会誌, 大気環境学会誌, 51(3), 161 - 173, May 2016
  • Effect of Fetch on a Mechanism for Pollutant Removal from a Two-Dimensional Street Canyon, Takenobu Michioka, Hiroshi Takimoto, Hiroki Ono, Ayumu Sato, Boundary-Layer Meteorology, Boundary-Layer Meteorology, 1 - 15, Feb. 2016
    Summary:© 2016 Springer Science+Business Media DordrechtLarge-eddy simulation is conducted to investigate the effect of fetch on the pollutant-removal mechanism from a two-dimensional street canyon with a building-height to street-width (aspect) ratio of 1. The line sources were placed within the first, second, third, fifth, seventh and tenth canyons, and the six tracer gases are simultaneously released by a ground-level continuous pollutant line source placed parallel to the spanwise axis at the canyons. The mean concentration and the deviation of the concentration fluctuation within the canyon roughly reach a near-constant value downwind of the seventh canyon, which is similar to the behaviour of the turbulent intensities. In the first canyon, pollutant removal is affected by both advective flow and turbulent flow; however, the turbulent motions mainly affect pollutant removal from the top of the canyon as the fetch increases. In the first and third canyons, the low-momentum fluid does not always affect pollutant removal, but does so gradually as the fetch increases.
  • Prediction of a visible plume from a dry and wet combined cooling tower and its mechanism of abatement, Kazutaka Takata, Takenobu Michioka, Ryoichi Kurose, Atmosphere, Atmosphere, 7, Jan. 01 2016
    Summary:© 2016 by the authors.Heated moist air from a cooling tower forms a visible plume and needs to be predicted, not only for the performance design of the cooling tower, but also for environmental impact assessments. In this study, a computational fluid dynamics analysis is conducted to predict the scale of a visible plume rising from a cross flow cooling tower with mechanical draft (provided by a rotating fan). The results of computational fluid dynamics analysis are verified by comparing predictions with an actual observed plume. The results show that the predicted visible plume represents the observed plume in an error range of 15%-20%, which is permissible for designing a cooling tower. Additionally, the mixing condition of heated dry air and moist air under dry and wet combined operation is examined, and the condition is thought to affect the scale of the visible plume. It is found that, in the case of a mechanical-draft cooling tower, the fan has a mixing function which performs the complete mixing of wet and dry air, and this suggests that the generation of the plume can be determined by the intersection of the operation line and saturation line. Additionally, the effect of external wind on the scale of the visible plume is large, especially for dry and wet combined operation.
  • Effect of additional structure on effective stack height of gas dispersion in atmosphere, Takenobu Michioka, Koichi Sada, Kazuki Okabayashi, Atmosphere, Atmosphere, 7, Jan. 2016
    Summary:© 2016 by the authors.Wind-tunnel experiments were conducted to evaluate the effect of additional structure (building, sea wall and banking) on the effective stack height, which is usually used in safety analyses of nuclear power facilities in Japan. The effective stack heights were estimated with and without the additional structure in addition to the reactor building while varying several conditions such as the source height, the height of additional structure and the distance between the source position and the additional structure. When the source height is equivalent to the reactor building height, the additional structure enhances both the vertical and horizontal gas dispersion widths and decreases the ground gas concentration, and it means that the additional structure does not decrease the effective stack height. When the source height is larger than the reactor height, the additional structures might affect the effective stack height. As the distance between the source and the additional structure decreases, or as the height of the additional structure increases, the structure has a larger effect on the effective stack height.
  • CONVECTION TERM DISCRETIZATION FOR LARGE EDDY SIMULATIONS BASED ON THE FINITE VOLUME METHOD Effect of thermal stratification on the dispersion characteristics of rooftop exhaust, Part 2, 小野浩己, 瀧本浩史, 道岡武信, 佐藤歩, 日本建築学会環境系論文集, 日本建築学会環境系論文集, (718), 1143 - 1151, Dec. 2015
  • A Wind-tunnel Study of Atmospheric Dispersion of Cooling-tower Exhaust over a Simple Hill: Influences of Plume Rise and Surface Roughness of the Terrain, 瀧本浩史, 小野浩己, 佐藤歩, 道岡武信, 佐田幸一, 大気環境学会誌, 大気環境学会誌, 50(5), 226 - 232, Sep. 2015
  • WIND TUNNEL EXPERIMENT OF CONTAMINANT DISPERSION FROM SIMPLIFIED BUILDING UNDER STABLY STRATIFIED FLOW : Effect of thermal stratification on dispersion characteristics from rooftop exhaust(Part 1), 小野 浩己, 瀧本 浩史, 道岡 武信, 日本建築学会環境系論文集, 日本建築学会環境系論文集, 79(701), 607 - 613, Jul. 2014
  • Characterization of Long-Term Used De-NO_x Catalyst, TANNO Kenji, NODA Naoki, YAMAMOTO Toru, KUROSE Ryoichi, MICHIOKA Takenobu, MAKINO Hisao, 粉体工学会誌, 粉体工学会誌, 50(10), 733 - 740, Oct. 10 2013
  • Direct numerical simulation of flow and surface reaction in de-NO x catalyst, Kenji Tanno, Ryoichi Kurose, Takenobu Michioka, Hisao Makino, Satoru Komori, Advanced Powder Technology, Advanced Powder Technology, 24, 879 - 885, Sep. 01 2013
    Summary:Selective catalytic reaction is a very efficient method to reduce NO x emissions from thermal power plants and is widely used in Japan. To develop a higher performance de-NOx system and optimize its maintenance schedule, it is important to understand the NOx reduction mechanism in the honeycomb channel which supports the de-NOx catalysts. In this study, the effects of duct channel flow behavior on the de-NOx reaction at the catalyst surface were investigated using a direct numerical simulation (DNS). The DNS computations were performed for three inflow conditions, one laminar and two turbulent. The results show that although the flow transitions from turbulent to laminar flow as the flow moves downstream for the turbulent inflow conditions, de-NOx reaction rates for the turbulent inflow conditions are higher than that for the laminar inflow condition even in the downstream region. This is because of the remaining cross-sectional fluid motions caused by the inflow turbulence. As a result, de-NOx efficiencies for the turbulent conditions are higher than that for the laminar case. For both laminar and turbulent inflow conditions, de-NOx reaction is suppressed in the corner regions due to the flow stagnation. © 2013 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.
  • Large-eddy simulation coupled to mesoscale meteorological model for gas dispersion in an urban district, T. Michioka, A. Sato, K. Sada, Atmospheric Environment, Atmospheric Environment, 75, 153 - 162, Aug. 01 2013
    Summary:A microscale large-eddy simulation (LES) model coupled to a mesoscale LES model is implemented to estimate a ground concentration considering the meteorological influence in an actual urban district. The microscale LES model is based on a finite volume method with an unstructured grid system to resolve the flow structure in a complex geometry. The Advanced Regional Prediction System (ARPS) is used for mesoscale meteorological simulation. To evaluate the performance of the LES model, 1-h averaged concentrations are compared with those obtained by field measurements, which were conducted for tracer gas dispersion from a point source on the roof of a tall building in Tokyo. The concentrations obtained by the LES model without combing the mesoscale LES model are in quite good agreement with the wind-tunnel experimental data, but overestimates the 1 h averaged ground concentration in the field measurements. On the other hand, the ground concentrations using the microscale LES model coupled to the mesoscale LES are widely distributed owing to large-scale turbulent motions generated by the mesoscale LES, and the concentrations are nearly equal to the concentrations from the field measurements. © 2013 Elsevier Ltd.
  • Length-Scale Similarity of Turbulent Organized Structures over Surfaces with Different Roughness Types, Hiroshi Takimoto, Atsushi Inagaki, Manabu Kanda, Ayumu Sato, Takenobu Michioka, Boundary-Layer Meteorology, Boundary-Layer Meteorology, 147, 217 - 236, May 01 2013
    Summary:We examine the similarity of turbulent organized structures over smooth and very rough wall flows. Turbulent flow fields in horizontal cross-sections were measured using particle image velocimetry, and the characteristics of turbulent organized structures over four types of surfaces were investigated. Measurements were conducted at several measurement heights across the internal boundary layer. The length and width of turbulence structures were quantified using a two-point correlation method. We selected two thresholds of two-point correlation coefficients to consider both large-scale and small-scale structures; the validity of these choices was examined through the analyses using proper orthogonal decomposition. For large-scale structures, the length and aspect ratios (streamwise length/spanwise width) of structures were highly correlated with the velocity gradient for each measurement height and boundary-layer thickness. This relationship was also examined in the results of previous studies, and the scaling of the aspect ratio with the non-dimensional velocity gradient again showed the importance of the velocity gradient, with slight differences found between smooth and rough surfaces. In contrast, the small-scale structures exhibited weak dependency on the velocity gradient and boundary-layer thickness. Instantaneous snapshots of turbulent organized structures at the same shear level also displayed differences in small-scale structures, but the structures of the organized motions resembled each other, as in the results of the two-point correlation method. © 2012 Springer Science+Business Media Dordrecht.
  • Effect of Particle Collision and Rebound Behavior on Adhesion Characteristics on the Wall of Honeycomb Shaped Catalyst, TANNO Kenji, KUROSE Ryoichi, MICHIOKA Takenobu, MAKINO Hisao, KOMORI Satoru, 粉体工学会誌, 粉体工学会誌, 50(3), 204 - 211, Mar. 10 2013
  • Characterization of Long-Term Used De-NOx Catalyst, Tanno Kenji, Noda Naoki, Yamamoto Toru, Kurose Ryoichi, Michioka Takenobu, Makino Hisao, Journal of the Research Association of Powder Technology, Japan, Journal of the Research Association of Powder Technology, Japan, 50(10), 733 - 740, 2013
    Summary:In coal-fired power plants, selective catalytic de-NOx systems are widely used and offer a very efficient method to reduce NOx emissions from such plants. However, de-NOx catalyst degrades in long-term operation and catalysts must be periodically exchanged. Exchange of catalysts costs a great deal, hence there is a strong economic incentive to elucidate the degradation mechanism of catalysts and optimize the operation conditions of de-NOx equipment. In this study, fluorescent X-ray analysis is performed to investigate the elemental distribution on the catalyst surface. Also, X-ray absorption fine structure (XAFS) analysis is applied to determine the chemical form of Vanadium in the catalyst. The results show that elements found in fly ash are detectable in the upstream region near the inlet, whereas such elements are not detected in the downstream region near the outlet. This tendency is in good qualitative agreement with the author's previous numerical result. Vanadium in the fresh catalyst is mainly in its 3+ valence state, whereas that in used catalyst is mainly in the 4+ or 5+ valence states. The ratio of vanadium in 5+ valence state is larger in the inlet region than in the downstream region. This is due to turbulent eddy mixing which promotes vanadium oxidation in the inlet region.
  • Effect of Particle Collision and Rebound Behavior on Adhesion Characteristics on the Wall of Honeycomb Shaped Catalyst, Tanno Kenji, Kurose Ryoichi, Michioka Takenobu, Makino Hisao, Komori Satoru, Journal of the Research Association of Powder Technology, Japan, Journal of the Research Association of Powder Technology, Japan, 50(3), 204 - 211, 2013
    Summary:In coal-fired thermal power plants, selective catalytic de-NOx system is widely used and very efficient method to reduce NOx emission from the plant. However, ash particles laden in flue gas adhere on a de-NOx catalyst surface, and ash coverage causes the severe degradation of de-NOx catalyst. Authors numerically investigated the effect of flow behavior in a honeycomb channel on the adhesion characteristics of particles to the wall in the previous study. However, previous study was performed under the assumption that all particles, which reach the wall, adhere. Therefore, in this study, the effect of particle collision and rebound behavior on the adhesion characteristics on the wall of honeycomb shaped catalyst was investigated by applying a direct numerical simulation (DNS). In order to take account of particle collision and rebound behavior, the probability coefficient of adhesion was introduced. The results show that although particle adheres on the wall only in the upstream region, in which flow condition is turbulent, irrespective of adhesion probability coefficient, the amount of adhered particles decreases with decreasing probability coefficient. The results also indicate that particle re-adhesion also occurs only in the upstream region even though some particle rebound and return to the flow from the wall.
  • Effect of Incoming Turbulent Structure on Pollutant Removal from Two-Dimensional Street Canyon, Takenobu Michioka, Ayumu Sato, Boundary-Layer Meteorology, Boundary-Layer Meteorology, 145, 469 - 484, Dec. 01 2012
    Summary:Large-eddy simulations are conducted to investigate the effects of the incoming turbulent structure of the flow on pollutant removal from an ideal canyon. The target canyon is a two-dimensional street canyon with an aspect ratio of 1. 0 (building height to street width). Three turbulent flows upwind of the street canyon are generated by using different block configurations, and a tracer gas is released as a ground-level line source at the centre of the canyon floor. Mean velocity profiles for the three flows are similar, except near the roof. However, the root-mean-square values of the velocity fluctuations and the Reynolds shear stress increase with the friction velocity of the incoming turbulent flow. The spatially-averaged concentration within the canyon decreases with increasing friction velocity. Coherent structures of low-momentum fluid, generated above the upwind block configurations, contribute to pollutant removal, and the amount of pollutant removal is directly related to the size of the coherent structure. © 2012 Springer Science+Business Media B.V.
  • Development of numerical model of stack gas diffusion under terrain condition : Applications of numerical model to high stacks, SADA Koichi, SATO Ayumu, MICHIOKA Takenobu, ICHIKAWA Yoichi, 大気環境学会誌 = Journal of Japan Society for Atmospheric Environment, 大気環境学会誌 = Journal of Japan Society for Atmospheric Environment, 47(6), 261 - 269, Nov. 10 2012
  • Effect of Flow Behavior in Honeycomb Channel on Characteristics of Particle Adhesion to the Wall, TANNO Kenji, KUROSE Ryoichi, MICHIOKA Takenobu, MAKINO Hisao, KOMORI Satoru, Journal of the Research Association of Powder Technology, Japan, Journal of the Research Association of Powder Technology, Japan, 49(10), 738 - 744, Oct. 10 2012
    Summary:In a coal-fired thermal power plant, ash particles laden in flue gas adhere on de-NOx catalyst surface, and ash coverage causes the degradation of de-NOx catalyst. Therefore, in this study, effect of the flow in a honeycomb rectangular channel, which represents a single channel of de-NOx catalyst, on the adhesion characteristics of particles to the wall was investigated by applying a direct numerical simulation (DNS). Results show that the adhesion of particles is strongly affected by the flow. The particle adhesion is enhanced by turbulence near the inlet of channel, whereas suppressed due to the attenuation of turbulence in the downstream region. The particle adhesion also depends on particle diameter. Small particles adhere on the wall only in the upstream region, whereas large particles adhere all the way down to outlet, nevertheless flow transients to laminar. This is due to the fact that large particles keep the inertial force even in the downstream region. Moreover, the cross sectional position of particle adhesion also depends on both flow stagnation near the corner and a secondary flow which is driven on the plane normal to the streamwise direction.
  • Numerical simulation of air flow and gas dispersion in urban districts, MICHIOKA Takenobu, SATO Ayumu, 大気環境学会誌 = Journal of Japan Society for Atmospheric Environment, 大気環境学会誌 = Journal of Japan Society for Atmospheric Environment, 47(3), 119 - 126, May 10 2012
  • Subgrid scale scalar variance in high-Schmidt-number turbulence, Ryoichi Kurose, Naohisa Takagaki, Takenobu Michioka, Naoki Kohno, Satoru Komori, AIChE Journal, AIChE Journal, 58, 377 - 384, Feb. 01 2012
    Summary:The subgrid scale (SGS) variance for a high-Schmidt-number passive scalar of Sc >> 1 is measured using a high-resolution planar laser-induced fluorescence technique in a grid-generated turbulent liquid flow, and the values of the model coefficients in the scale-similarity model and the scalar-gradient model used for estimating the SGS scalar variance are experimentally evaluated. The results show that for both models, the measured values are much larger than the well-known values obtained in the previous studies done for non-high-Sc scalars of Sc ≅ 1. Similarly, the measured value of the model coefficient in the scalar-gradient model tends to be larger than the value estimated by the dynamic procedure. The increases in the measured values of the model coefficients for the high-Sc scalar can be explained by the presence of the viscous-convective range showing a nearly (-1)-slope in the high-wavenumber range of the power spectrum of concentration fluctuation. © 2011 American Institute of Chemical Engineers (AIChE).
  • LARGE-EDDY SIMULATION FOR AIRFLOW AND THERMAL DIFFUSION IN AN URBAN CANYON, MICHIOKA Takenobu, SATO Ayumu, PROCEEDINGS OF THE JAPANESE CONFERENCE ON HYDRAULICS, PROCEEDINGS OF THE JAPANESE CONFERENCE ON HYDRAULICS, 68(4), I_1795 - I_1800, 2012
    Summary:Large-eddy simulation was implemented for airflow and thermal diffusion in an urban canyon. To evaluate the performance of the LES, the mean velocities, standard deviations of turbulent fluctuations and mean temperature estimated by the LES are compared with those obtained by wind-tunnel experiments. The results show that the LES can capture the flow and temperature within the canyon, and accurately represent the effect of the wall heating on flow within the canyon. Though the previous studies only focused on the vertical cross section, it is found that two axisymmetrical vortexes are formed in the horizontal cross section with a large clockwise vortex in vertical cross section irrespective of the wall heating conditions. The horizontal vortexes are enlarged by wall heating, and horizontal turbulent fluctuations are increased. Thus, the thermal environment within the canyon is affected not only by the vertical large vortex, but also by the horizontal turbulent flow.
  • Field experiments of flow and dispersion within a street canyon in outdoor urban scale model, A. Sato, T. Michioka, H. Takimoto, International Journal of Environment and Pollution, International Journal of Environment and Pollution, 47, 184 - 192, Dec. 01 2011
    Summary:Field experiments of air flow and pollution dispersion within a street canyon in the Comprehensive Outdoor Scale Model (COSMO) facility were conducted to investigate the effect of the mean and turbulent flow above the canyon on pollutant dispersion inside the canyon. Tracer gas concentration was measured using fast-response photo ionisation detectors. Three-dimensional wind velocity components were also simultaneously measured using ultrasonic anemometers within and above the same canyon. Using both tracer gas concentration and velocity fluctuation data, we investigated the effects of atmospheric turbulence above the height of the buildings on pollution dispersion within the street canyon. Copyright © 2011 Inderscience Enterprises Ltd.
  • Wind-Tunnel Experiments for Gas Dispersion in an Atmospheric Boundary Layer with Large-Scale Turbulent Motion, Takenobu Michioka, Ayumu Sato, Koichi Sada, Boundary-Layer Meteorology, Boundary-Layer Meteorology, 141, 35 - 51, Oct. 01 2011
    Summary:Large-scale turbulent motions enhancing horizontal gas spread in an atmospheric boundary layer are simulated in a wind-tunnel experiment. The large-scale turbulent motions can be generated using an active grid installed at the front of the test section in the wind tunnel, when appropriate parameters for the angular deflection and the rotation speed are chosen. The power spectra of vertical velocity fluctuations are unchanged with and without the active grid because they are strongly affected by the surface. The power spectra of both streamwise and lateral velocity fluctuations with the active grid increase in the low frequency region, and are closer to the empirical relations inferred from field observations. The large-scale turbulent motions do not affect the Reynolds shear stress, but change the balance of the processes involved. The relative contributions of ejections to sweeps are suppressed by large-scale turbulent motions, indicating that the motions behave as sweep events. The lateral gas spread is enhanced by the lateral large-scale turbulent motions generated by the active grid. The large-scale motions, however, do not affect the vertical velocity fluctuations near the surface, resulting in their having a minimal effect on the vertical gas spread. The peak concentration normalized using the root-mean-squared value of concentration fluctuation is remarkably constant over most regions of the plume irrespective of the operation of the active grid. © 2011 Springer Science+Business Media B.V.
  • Application of flamelet model to large-eddy simulation of turbulent reacting liquid flows, Ryoichi Kurose, Takenobu Michioka, Naoki Kohno, Satoru Komori, Yuya Baba, AIChE Journal, AIChE Journal, 57, 911 - 917, Apr. 01 2011
    Summary:Large-eddy simulations using the flamelet models are applied to turbulent reacting liquid flows and validated by comparing with the experiments. The computations are performed for two reaction conditions, namely a rapid reaction and a moderately fast reaction in a grid-generated turbulent flow. For the flamelet models, both the steady flamelet model and the unsteady Lagrangian flamelet model are tested. A second-order, irreversible, and isothermal reaction is considered. The results show that the flamelet models inherently developed for turbulent combustion are applicable to turbulent reacting liquid flows, provided that the model coefficient in evaluating the subgrid scale variance of mixture fraction in the scale-similarity model is set to be 5.0. The rapid reaction can be adequately predicted by both the steady and unsteady Lagrangian flamelet models, whereas the moderately fast reaction can be predicted only by the unsteady Lagrangian flamelet model which is capable to take slow chemical processes into account. © 2010 American Institute of Chemical Engineers (AIChE).
  • Large-Eddy Simulation for the Mechanism of Pollutant Removal from a Two-Dimensional Street Canyon, Takenobu Michioka, Ayumu Sato, Hiroshi Takimoto, Manabu Kanda, Boundary-Layer Meteorology, Boundary-Layer Meteorology, 138, 195 - 213, Jan. 01 2011
    Summary:Large-eddy simulation (LES) is conducted to investigate the mechanism of pollutant removal from a two-dimensional street canyon with a building-height to street-width (aspect) ratio of 1. A pollutant is released as a ground-level line source at the centre of the canyon floor. The mean velocities, turbulent fluctuations, and mean pollutant concentration estimated by LES are in good agreement with those obtained by wind-tunnel experiments. Pollutant removal from the canyon is mainly determined by turbulent motions, except in the adjacent area to the windward wall. The turbulent motions are composed of small vortices and small-scale coherent structures of low-momentum fluid generated close to the plane of the roof. Although both small vortices and small-scale coherent structures affect pollutant removal, the pollutant is largely emitted from the canyon by ejection of low-momentum fluid when the small-scale coherent structures appear just above the canyon where the pollutant is retained. Large-scale coherent structures also develop above the canyon, but they do not always affect pollutant removal. © 2010 Springer Science+Business Media B.V.
  • Wind Tunnel Experiments for Simulating Turbulent Motions in a Real Atmospheric Boundary Layer(Fluids Engineering), MICHIOKA Takenobu, SATO Ayumu, HATTORI Yasuo, Transactions of the Japan Society of Mechanical Engineers. B, Transactions of the Japan Society of Mechanical Engineers. B, 76(765), 823 - 829, May 25 2010
    Summary:A wind tunnel experiment was conducted to simulate large-scale turbulent motions in an atmospheric boundary layer (ABL). The large-scale turbulent motions originating from outer-layer disturbance were generated using an active grid installed at the front of the test section and the winglets of the active grid were randomly rotated. The large-scale horizontal motions in the ABL were generated in the wind tunnel using the active grid when appropriate values of the angle and rotation speed were chosen. The validity of the present method using the active grid was confirmed by comparing the integral scale and energy spectra obtained by the experiments with empirical formulas inferred from field observations. This indicates that the present method of using the active grid accurately simulates the turbulent motions in a nearly neutral ABL.
  • Development of Prediction Method for a Visible Plume from a Mechanical Draft-Cooling Tower : 2nd Report, Numerical Simulation to Predict a Visible Plume(Fluids Engineering), MICHIOKA Takenobu, SATO Ayumu, SADA Koichi, Transactions of the Japan Society of Mechanical Engineers. B, Transactions of the Japan Society of Mechanical Engineers. B, 75(752), 604 - 611, Apr. 25 2009
    Summary:A Large-eddy simulation (LES) was developed to predict a visible plume region from a mechanical-draft cooling tower. This numerical model solves the equations for conservation of mass, momentum, energy, vapor and liquid water. It is assumed that the visible plume is generated whenever the instantaneous liquid water mixing ratio is existed. To estimate the accuracy of the present numerical model, the predictions of visible plume length and height are compared with observations. The results show the visible plume length and height are in good agreement with the observations. Furthermore, we investigate the basic behavior of the visible plume and temperature emitted from the cooling tower under severe metrological condition. It is found that whether the visible plume reaches the ground or not mostly depends on the wind angle to the cooling tower, and temperature emitted from the cooling tower has little influence on atmosphere environment on the ground.
  • Development of Prediction Method for a Visible Plume from a Mechanical Draft-Cooling Tower : 1st Report, Wind Tunnel Experiments to Predict a Visible Plume(Fluids Engineering), MICHIOKA Takenobu, SATO Ayumu, SADA Koichi, Transactions of the Japan Society of Mechanical Engineers. B, Transactions of the Japan Society of Mechanical Engineers. B, 75(749), 93 - 100, Jan. 25 2009
    Summary:We developed a method for a wind tunnel experiment to predict a visible plume region from a mechanical-draft cooling tower. The diffusions of water vapor and temperature emitted from the cooling tower in the wind tunnel experiment are tracked using tracer gas. It is assumed that the plume-induced fog is generated whenever the instantaneous specific humidity predicted from the concentration of the tracer gas at measuring points is larger than the inferred saturation specific humidity. To estimate the accuracy of the present method, the measurements are compared with the observations. The results show that the visible plume length and height are in good agreement with the observations. Furthermore, it is found that the visible length and height is strongly affected by wind direction to the cooling tower, temperature difference between atmosphere and exit of the cooling tower and atmospheric humidity, and hence the present wind tunnel method considered these conditions is valid to predict the visible plume.
  • The visible plume model for a mechanical-draft cooling tower-Field campaign for visible plume measurements-:-Field campaign for visible plume measurements-, Shimota Akiro, Michioka Takenobu, Sada Koichi, Sato Ayumu, Kanzaki Takao, Wada Koji, Ichikawa Yoichi, Journal of Japan Society of Air Pollution, Journal of Japan Society of Air Pollution, 44(5), 255 - 261, 2009
    Summary:Recently, power plant's cooling towers equipped with instruments for preventing plume to visualize, which is a mechanical-draft cooling tower, tend to be planned and be constructed in Japan. Traditional ways of environmental assessment for a cooling tower has adopted a visible plume prediction model based on a natural-draft cooling tower. The requirement of developing new visible plume model having capability of prediction of visible plume, temperature, moisture and droplet from a mechanical-draft cooling tower is rising up. A field campaign to obtain data from a power plant with a mechanical-draft cooling tower for evaluation and validation of a new visible plume model and some conventional models is conducted. Measurements of surface temperature and humidity distribution around the plant does not show a clear effect of visible plume. Over 100 pairs of visible plume height and length are obtained by using video cameras and thermographyies Furthermore, droplet from the cooling tower shows very few amounts at a ground because of adopting to it a eliminator for preventing droplet scattering.
  • Visible plume model for a mechanical-draft cooling tower-Development of the visible plume model-:-Development of the visible plume model, Michioka Takenobu, Sato Ayumu, Shimota Akiro, Sada Koichi, Ichikawa Yoichi, Okura Arata, Journal of Japan Society of Air Pollution, Journal of Japan Society of Air Pollution, 44(5), 227 - 235, 2009
    Summary:A new visible plume model is developed to predict visible plume, temperature, moisture and droplet from a mechanical-draft cooling tower. The developed model is a normal Gaussian plume model for moisture and temperature, considering fan configuration, wet-dry combined cooling tower system, vertical atmospheric temperature and atmospheric stability. The accuracy of previous models (FOG, SACTI) and the developed model is investigated to compare the model results with observation conducted in Japan. The results show that the previous models can not accurately predict the visible plume length and height because they have mainly developed for a natural-drift cooling tower, which is different type from a mechanical-draft cooling tower. On the other hand, the visible plume length and height predicted by the developed model are in good agreement with the observation, and statistical data analysis also shows that the model provides better performance than the previous models. Furthermore, the model predicts not only the visible plume region but also temperature, moisture and droplet from the cooling tower.
  • Visible plume model for a mechanical-draft cooling tower-Development of the plume height and diffusion models-:-Development of the plume height and diffusion models-, Michioka Takenobu, Sato Ayumu, Sada Koichi, Shimota Akiro, Ichikawa Yoichi, Journal of Japan Society of Air Pollution, Journal of Japan Society of Air Pollution, 44(3), 147 - 154, 2009
    Summary:We developed new plume rise and diffusion models for gas dispersion from a mechanical-draft cooling tower. Wind tunnel experiments were conducted to investigate effects of fan location and cooling tower configuration on gas dispersion from the cooling towers. The results show that cooling tower configuration does not affect the plume rise and diffusion, but the fan location and numbers strongly affect them. The plume rise increases with the fun number in case of the fans located in downwind direction, but it is comparable level to the single fan in case of orthogonally-aligned fans to the wind direction. In addition, the vertical and horizontal diffusion becomes large as the fan number increases. These effects are not considered by the previous Gaussian type model (FOG model), generating the large difference of the plume rise and dispersion between the model and the wind tunnel experiment. On the other hand, the developed models considering the fan location and number can accurately estimate the plume rise and diffusion from the mechanical-draft cooling towers.
  • Numerical model for stack gas diffusion in terrain containing buildings - Application of numerical model to a cubical building and a ridge terrain, Koichi Sada, Takenobu Michioka, Yoichi Ichikawa, Asian Journal of Atmospheric Environment, Asian Journal of Atmospheric Environment, 2, 1 - 13, Jun. 01 2008
    Summary:A numerical simulation method has been developed to predict atmospheric flow and stack gas diffusion using a calculation domain of several km around a stack under complex terrain conditions containing buildings. The turbulence closure technique using a modified k-ε-type model under a nonhydrostatic assumption was used for the flow calculation, and some of the calculation grids near the ground were treated as buildings using a terrain-following coordinate system. Stack gas diffusion was predicted using the Lagrangian particle model, that is, the stack gas was represented by the trajectories of released particles. The numerical model was applied separately to the flow and stack gas diffusion around a cubical building and to a two-dimensional ridge in this study, before being applied to an actual terrain containing buildings in our next study. The calculated flow and stack gas diffusion results were compared with those obtained by wind tunnel experiments, and the features of flow and stack gas diffusion, such as the increase in turbulent kinetic energy and the plume spreads of the stack gas behind the building and ridge, were reproduced by both calculations and wind tunnel experiments. Furthermore, the calculated profiles of the mean velocity, turbulent kinetic energy and concentration of the stack gas around the cubical building and the ridge showed good agreement with those of wind tunnel experiments.
  • WIND TUNNEL EXPERIMENT OF FLOW BEHIND A CUBICAL BUILDING UNDER UNSTABLE STRATIFICATION, SATO AYUMU, TAKIMOTO HIROSHI, MICHIOKA TAKENOBU, PROCEEDINGS OF NATIONAL SYMPOSIUM ON WIND ENGINEERING, PROCEEDINGS OF NATIONAL SYMPOSIUM ON WIND ENGINEERING, 20(0), 21 - 21, 2008
    Summary:A wind tunnel experiment was conducted to investigate the effects of unstable stratification on cavity flow behind a cubical building. Mean and fluctuation velocities were measured by both laser Doppler anemometry and particle image velocimetry in the thermally stratified wind tunnel. Although both mean and fluctuation velocity components showed similar profiles in the near wake of the building under neutral and unstable conditions, turbulent intensities showed higher values in the far wake in unstable stratified flow owing to strong vertical mixing. In particular, as the unstable stratification became stronger, the circular vortex behind the trailing edge of the building tended not to be formed because separation vortices shed from the roof were greatly disturbed by buoyancy.
  • Wind tunnel experiment for predicting a visible plume region from a wet cooling tower, Takenobu Michioka, Ayumu Sato, Takao Kanzaki, Kouichi Sada, Journal of Wind Engineering and Industrial Aerodynamics, Journal of Wind Engineering and Industrial Aerodynamics, 95, 741 - 754, Aug. 01 2007
    Summary:We developed a new method for a wind tunnel experiment to predict a visible plume region from a wet cooling tower. The diffusion of water vapor and heat emitted from a cooling tower in a wind tunnel is estimated using a tracer gas. The instantaneous concentration of the tracer gas is measured using high-response flame ionization detectors. A moist plume-induced fog is assumed to be generated whenever the instantaneous specific humidity predicted from the concentration of the tracer gas at measured points is larger than the inferred saturation specific humidity. To confirm the validity of the present method, the results in the wind tunnel experiments are roughly compared with the observations obtained at the mechanical-draft cooling tower of the Benning Road plant. The results show that the visible plume length and height are nearly in agreement with observations and the present method has the capability to predict the visible plume region from the cooling tower. © 2007 Elsevier Ltd. All rights reserved.
  • Large-Eddy Simulation of Particle Diffusion in a Particle-laden Swirling Jet, MICHIOKA Takenobu, KUROSE Ryoichi, Transactions of the Japan Society of Mechanical Engineers Series C, Transactions of the Japan Society of Mechanical Engineers Series C, 73(725), 30 - 37, 2007
    Summary:Three-dimensional large-eddy simulation (LES) is applied to a particle-laden swirling jet, and the effect of swirl on particle diffusion is investigated. The trajectories of all particles are individually pursued with a Lagrangian method. The particles with different diameters are uniformly injected into the non-swirling and swirling flows with different Swirling numbers. The result shows that the trajectories of the particles with different diameters are quite different. The smaller particles have the peak of the particle number densities at central axis, and diffuse across swirling jet. On the other hand, the larger particles at the exit of the nozzle migrate outward by the centrifugal force, but the particles gradually migrate inward with the axial distance increases. The inward movement of the particle in the downstream region is dominated by turbulent motions, which transport the particles inward near central axis. Furthermore, above behavior is shifted upstream with the particle diameter decrease because the smaller particles are easily transferred by smaller inward fluid motions existing in the wide range of the swirling jet.
  • Effect of Flow Behavior in De-NOx Catalyst Honeycomb on Adhesion of Particles to the Wall, Kurose Ryoichi, Michioka Takenobu, Makino Hisao, Komori Satoru, Journal of the Research Association of Powder Technology, Japan, Journal of the Research Association of Powder Technology, Japan, 44(2), 107 - 112, 2007
    Summary:Effect of flow behavior in a honeycomb rectangular channel of a de-NOX catalyst on the adhesion of particles onto the wall is studied using a direct numerical simulation (DNS). The results show that the adhesion of particles is markedly affected by the turbulent-laminar-transition flow and is enhanced by the turbulence in the upstream region near the inlet. This agrees well with the previous experimental observation, in which the degradation of catalyst appeared in the region near the inlet. The adhesion of particles is found to be enhanced by the turbulence especially for larger particles. In the downstream region, the adhesion on the wall near the corners of rectangular channels is suppressed since the turbulent-laminar transition proceeds from these regions.
  • Direct numerical simulation of a particle-laden mixing layer with a chemical reaction, Takenobu Michioka, Ryoichi Kurose, Ryoichi Kurose, Kouichi Sada, Hisao Makino, International Journal of Multiphase Flow, International Journal of Multiphase Flow, 31, 843 - 866, Jul. 01 2005
    Summary:A direct numerical simulation (DNS) is applied to a particle-laden turbulent mixing layer with a chemical reaction, and the effects of particles on turbulence and chemical species' diffusion and reaction in both zero and finite gravity cases are investigated. Unreactive particles, whose response time, τP, is smaller than the Kolmogorov time scale, τK [τP/τK = O(10-1)], are uniformly injected into the high-speed side of the mixing layer. Two reactive chemical species are separately introduced through different sides. The results show that although laden particles generally depress turbulent intensities, they begin to enhance turbulent intensities downstream as the particle size decreases provided that the inlet particle volume fraction is fixed. This is because that the small particles with small particle response time easily accumulate at the circumference of coherent vortices and act to suppress the growth of primitive small-scale coherent vortices upstream but enhance that of relatively developing large-scale ones downstream. Also, since the small-scale turbulence, which promotes the chemical reaction, is suppressed by the laden particles in the entire region, chemical product decreases overall. Furthermore, the presence of finite gravity on the particles acts to depress the turbulent intensities, but its effects on chemical species' diffusion and reaction are quite small. © 2005 Elsevier Ltd. All rights reserved.
  • Large-eddy simulation of a turbulent reacting liquid flow, Takenobu Michioka, Takenobu Michioka, Satoru Komori, AIChE Journal, AIChE Journal, 50, 2705 - 2720, Nov. 01 2004
    Summary:A subgrid-scale (SGS) model for the filtered reaction source term is presented to develop the large-eddy simulation (LES) of a nonpremixed, turbulent liquid flow with a moderately fast reaction. The SGS model is based on the SGS probability density function (PDF) and SGS conditional expectation. The SGS probability density function (SGS-PDF) is assumed to follow a beta distribution and a simple algebraic model for the SGS conditional expectation is developed using the filtered data obtained from the direct numerical simulation (DNS) of stationary isotropic liquid turbulence with a second-order chemical reaction. For a rapid reaction, the SGS-PDF model based on the conserved scalar is used as the SGS model. The LES based on these SGS models is applied to a liquid mixing layer flow downstream of a turbulence-generating grid with a chemical reaction, and the LES predictions of the mean concentration and concentration variance are directly compared with the previous measurements for both moderately fast and rapid reactions to examine the proposed SGS models. The results show that the predictions by the LES are in good agreement with the measurements and the present LES can well describe the diffusive-reactive process in a turbulent reacting liquid flow. © 2004 American Institute of Chemical Engineers.

Misc

  • 風向変動が都市キャノピー内のガス拡散に及ぼす影響, 道岡武信, 瀧本浩史, 小野浩己, 佐藤歩, 大気環境学会年会講演要旨集, 59th, 523,   2018 08 28 , https://jglobal.jst.go.jp/detail?JGLOBAL_ID=201802222933344409
  • 風向変動を考慮した都市キャノピー内のガス拡散を対象としたLES, 道岡武信, 瀧本浩史, 小野浩己, 佐藤歩, 数値流体力学シンポジウム講演論文集(CD-ROM), 32nd, ROMBUNNO.C04‐1,   2018 , https://jglobal.jst.go.jp/detail?JGLOBAL_ID=201902285781540809
  • 数値シミュレーションによる平塚観測塔周りの気流再現, 白石涼, 道岡武信, 鈴木直弥, 日本機械学会計算力学講演会論文集(CD-ROM), 30th, ROMBUNNO.043,   2017 09 15 , http://jglobal.jst.go.jp/public/201802243350188624
  • 風車周りのガス拡散を対象とした数値シミュレーション, 林将史, 道岡武信, 日本機械学会計算力学講演会論文集(CD-ROM), 30th, ROMBUNNO.042,   2017 09 15 , http://jglobal.jst.go.jp/public/201802286589239715
  • 空冷復水器から温風拡散に関する現地観測と予測モデルの構築, 瀧本浩史, 小野浩己, 佐藤歩, 岸田岳士, 道岡武信, 道岡武信, 大気環境学会年会講演要旨集, 58th, 557,   2017 08 28 , http://jglobal.jst.go.jp/public/201702216551751139
  • 風車ブレードの回転が排ガス拡散に及ぼす影響, 道岡武信, 林将史, 大気環境学会年会講演要旨集, 58th, 512,   2017 08 28 , http://jglobal.jst.go.jp/public/201702233419262738
  • 街区内で発達する乱流が汚染物質放出に及ぼす影響, 道岡武信, 瀧本浩史, 小野浩己, 佐藤歩, 数値流体力学シンポジウム講演論文集(CD-ROM), 31st, ROMBUNNO.B05‐1,   2017 , http://jglobal.jst.go.jp/public/201802247592221260
  • 地熱発電所から排出される硫化水素の大気拡散予測のための数値モデル開発, 小野浩己, 瀧本浩史, 佐藤歩, 道岡武信, 道岡武信, 大気環境学会年会講演要旨集, 57th, 184,   2016 08 29 , http://jglobal.jst.go.jp/public/201602217571401837
  • CFDモデルを用いた温室内の温熱空気環境評価, 後藤文之, 道岡武信, 庄子和博, 農業施設学会大会講演要旨, 2016, 113‐114,   2016 08 29 , http://jglobal.jst.go.jp/public/201602219413374495
  • 風向変動を考慮した都市キャニオン内のガス拡散, 道岡武信, 瀧本浩史, 小野浩己, 佐藤歩, 大気環境学会年会講演要旨集, 57th, 183,   2016 08 29 , http://jglobal.jst.go.jp/public/201602232825203893
  • 空冷復水器からの温風拡散を対象とした予測モデルの構築, 瀧本浩史, 小野浩己, 佐藤歩, 道岡武信, 道岡武信, 大気環境学会年会講演要旨集, 57th, 185,   2016 08 29 , http://jglobal.jst.go.jp/public/201602284478016948
  • 配電設備の風圧荷重評価における合理的な設計風速算定方法の提案, 村上貴裕, 石川智巳, 服部康男, 中尾圭佑, 道岡武信, 渡辺雅人, 篠崎孝一, 河口泰士, 電気学会全国大会講演論文集(CD-ROM), 2016, ROMBUNNO.7-114,   2016 03 05 , http://jglobal.jst.go.jp/public/201602220981186785
  • 波状壁上のガス拡散のレイノルズ数依存性, 道岡武信, 瀧本浩史, 小野浩己, 佐藤歩, 数値流体力学シンポジウム講演論文集(CD-ROM), 30th, ROMBUNNO.C06‐1,   2016 , http://jglobal.jst.go.jp/public/201702229433162191
  • 大気安定度を考慮した都市キャニオン内流れ場に関する風洞実験(その3)―数値シミュレーションとの比較―, 松本勇太, 香月壮亮, 道岡武信, 佐藤歩, 大気環境学会年会講演要旨集, 56th, 250,   2015 09 04 , http://jglobal.jst.go.jp/public/201502207078753742
  • 冷却塔からの排出拡散に対する建屋と地形の複合影響の検討, 瀧本浩史, 小野浩己, 佐藤歩, 道岡武信, 道岡武信, 大気環境学会年会講演要旨集, 56th, 186,   2015 09 04 , http://jglobal.jst.go.jp/public/201502207711439947
  • 山間部に設置された冷却塔からの排ガス拡散に関するLES, 小野浩己, 瀧本浩史, 佐藤歩, 道岡武信, 道岡武信, 大気環境学会年会講演要旨集, 56th, 185,   2015 09 04 , http://jglobal.jst.go.jp/public/201502217159224820
  • Applicability of a high-resolution meso-scale meteorological model to a near-field-scale atmospheric dispersion problem, 瀧本浩史, 道岡武信, 佐藤歩, 佐田幸一, 電力中央研究所原子力リスク研究センター研究報告, O14004, 25P,   2015 05 , http://jglobal.jst.go.jp/public/201602202655908276
  • 液相反応乱流場の濃度可視化について, 道岡武信, 可視化情報学会誌, 35, 137, 64-69,45(3),   2015 04 01 , 10.3154/jvs.35.137_20, http://jglobal.jst.go.jp/public/201502264275303573
  • 単純地形上のガス拡散に及ぼす安定温度成層の効果, 道岡武信, 瀧本浩史, 小野浩己, 佐藤歩, 数値流体力学シンポジウム講演論文集(CD-ROM), 29th, ROMBUNNO.A08-5,   2015 , http://jglobal.jst.go.jp/public/201602210778458014
  • 41321 A Study on Gas Dispersion from Rooftop of the Building under Neutral and Stable Atmospheric Stability, ONO Hiroki, TAKIMOTO Hiroshi, MICHIOKA Takenobu, SATO Ayumu, Summaries of technical papers of annual meeting, 2014, 0, 665, 666,   2014 09 12 , http://ci.nii.ac.jp/naid/110009855882
  • 地形影響を有する流れの数値計算に対する格子形状の影響, 小野浩己, 瀧本浩史, 佐藤歩, 道岡武信, 大気環境学会年会講演要旨集, 55th, 230,   2014 08 31 , http://jglobal.jst.go.jp/public/201402208480052414
  • 上昇過程を考慮した2次元尾根上の排ガス拡散に関する風洞実験, 瀧本浩史, 佐藤歩, 小野浩己, 道岡武信, 大気環境学会年会講演要旨集, 55th, 229,   2014 08 31 , http://jglobal.jst.go.jp/public/201402245343943738
  • 街区外乱流が街区内の汚染物質放出に及ぼす影響, 道岡武信, 瀧本浩史, 佐藤歩, 大気環境学会年会講演要旨集, 55th, 410,   2014 08 31 , http://jglobal.jst.go.jp/public/201402284140242918
  • 大気安定度を考慮した都市キャニオン内流れ場に関する風洞実験(その2)―大気安定度が都市キャニオン内の流れ場の構造に与える影響―, 香月壮亮, 道岡武信, 佐藤歩, 大気環境学会年会講演要旨集, 55th, 517,   2014 08 31 , http://jglobal.jst.go.jp/public/201402291705299630
  • 安定および中立の条件下における建物屋上面からの排ガス拡散性状の検討, 小野浩己, 瀧本浩史, 道岡武信, 佐藤歩, 日本建築学会大会学術講演梗概集・建築デザイン発表梗概集(CD-ROM), 2014, ROMBUNNO.41321,   2014 07 20 , http://jglobal.jst.go.jp/public/201402207567724218
  • Wind-tunnel experiments on wind attenuation within an urban canyon, 道岡武信, 服部康男, 瀧本浩史, 村上貴裕, 電力中央研究所環境科学研究所研究報告, V13016, 20P,   2014 05 , http://jglobal.jst.go.jp/public/201402241605684482
  • Wind tunnel experiment of contaminant dispersion from simplified building under stably stratified flow: Effect of thermal stratification on dispersion characteristics from rooftop exhaust: Part 1, Hiroki Ono, Hiroshi Takimoto, Takenobu Michioka, Auymu Sato, Journal of Environmental Engineering (Japan), 79, 607, 613,   2014 01 01 , 10.3130/aije.79.607, https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84907621107&origin=inward
    Summary:Wind tunnel experiments were carried on the concentration fields with rooftop exhaust under neutral and stably stratified flow. Mean velocity distribution behind the building was not affected by atmospheric stability, nevertheless turbulence intensity and contaminant distribution became quite different. Partial spread width was estimated with assuming Gaussian distribution; therefore it was found that strength of thermal stratification behind the building was attenuated locally by wake from the building.
  • Erratum: Direct numerical simulation of flow and surface reaction in de-NOx catalyst (Advanced Powder Technology 24:5 (879-885)), Kenji Tanno, Ryoichi Kurose, Takenobu Michioka, Hisao Makino, Satoru Komori, Advanced Powder Technology, 25, 476,   2014 01 01 , 10.1016/j.apt.2013.11.012, https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84896388217&origin=inward
  • Numerical simulations of stack-tip downwash with sub-critical reynolds numbers, Hiroshi Takimoto, Takenobu Michioka, Ayumu Sato, Hiroki Ono, HARMO 2014 - 16th International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes, Proceedings, 14, 18,   2014 01 01 , https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84983209084&origin=inward
    Summary:© Crown Copyright 2014 Dstl.Dispersion of effluent gases from the stacks of power plant facilities should be precisely predicted for the assessment of their environmental impacts. The replacement of Gaussian plume models by Computational Fluid Dynamics (CFD) models is expected to improve the accuracy of this prediction. In CFD models, it is desired to reproduce the plume rise process of discharged gases when the plume rise can be affected by nearby buildings or complex terrain. However, there are still many challenges to accomplish this purpose. In this study, we examined the influences of the mesh structure and mesh resolution around a stack on the accuracy of concentration predictions. Our results suggest that the unstructured grid is not appropriate to resolve the stacks, and the coarse grids lead to the underestimation of surface concentrations.
  • 地熱発電所に係る環境アセスメントのための硫化水素拡散予測数値モデルの開発, 佐藤歩, 道岡武信, 瀧本浩史, 小野浩己, 田浦恵三, 佐田幸一, 日本地熱学会学術講演会講演要旨集, 2014, OS2.6,   2014 , http://jglobal.jst.go.jp/public/201402238056235432
  • LESによる排ガス拡散計算のための放出源の設定に関する考察, 瀧本浩史, 道岡武信, 佐藤歩, 小野浩己, 大気環境学会年会講演要旨集, 54th, 203,   2013 08 31 , http://jglobal.jst.go.jp/public/201302246467441462
  • 大気安定度が建物周辺の拡散性状に及ぼす影響, 小野浩己, 瀧本浩史, 道岡武信, 佐藤歩, 大気環境学会年会講演要旨集, 54th, 202,   2013 08 31 , http://jglobal.jst.go.jp/public/201302285636350833
  • 実在都市キャニオン内の流れ場に関する検討(その4)―温熱環境評価のためのLES―, 道岡武信, 佐藤歩, 香月壮亮, 萩島理, 大気環境学会年会講演要旨集, 54th, 201,   2013 08 31 , http://jglobal.jst.go.jp/public/201302229978188038
  • 温度成層条件下における都市キャニオン内からの汚染物質放出挙動の検討, 道岡武信, 瀧本浩史, 佐藤歩, 大気環境学会年会講演要旨集, 54th, 200,   2013 08 31 , http://jglobal.jst.go.jp/public/201302297501234947
  • Building downwash of the plume from thermal power plants-Impacts of the stack height and emission speed of gases-, 瀧本浩史, 道岡武信, 佐藤歩, 電力中央研究所環境科学研究所研究報告, V12003, 23P,   2013 04 , http://jglobal.jst.go.jp/public/201302235479506525
  • Evaluation of thermal and air environment in plant factory (Part. 3)-Numerical simulation for plant factory with vegetation-, 道岡武信, 佐藤歩, 後藤文之, 瀧本浩史, 庄子和博, 電力中央研究所環境科学研究所研究報告, V12004, 20P,   2013 04 , http://jglobal.jst.go.jp/public/201302204622448148
  • 実在都市内の物質拡散シミュレーション, 道岡武信, 佐藤歩, 日本機械学会誌, 116, 1131, 97, 100,   2013 02 05 , http://jglobal.jst.go.jp/public/201302270030511770
  • Numerical Simulation of Gas Dispersion in a Real Urban, MICHIOKA Takenobu, SATO Ayumu, Journal of the Japan Society of Mechanical Engineers, 116, 1131, 97, 100,   2013 02 05 , http://ci.nii.ac.jp/naid/110009580268
  • Effect of turbulent to laminar flow transition on surface reaction and particle deposition in a square duct, Kenji Tanno, Hisao Makino, Ryoichi Kurose, Satoru Komori, Takenobu Michioka, International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2013, 2,   2013 01 01 , https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85032858114&origin=inward
    Summary:A monolith reactor is widely used to reduce pollutant matter in the industrial field. A monolith reactor, which consist of many rectangular channels, although flue gas flows into the channel inlet in turbulent condition, flue gas transitions from turbulent to laminar flow due to the small hydraulic diameter of a single channel. In order to develop a higher performance reactor, optimize the maintenance schedule and extend lifetime of reactor, it is important to understand reaction and degradation mechanism in a monolith reactor. In this study, surface reaction behaviour occurred on the wall and particle adhesion behaviour is investigated performing a direct numerical simulation (DNS). The results show that both surface reaction and particle adhesion are promoted by turbulent eddies which exists in the upstream region. However, the region which exhibits the effect of turbulent eddies is different. For particle deposition, the effect of turbulent eddies exhibits only in the upstream region, whereas for surface reaction, such effect also exhibits in the downstream region. This is because of the remaining cross-sectional fluid motion caused by the inflow turbulence. The magnitude of the cross-sectional fluid motion is weak, hence such motion only affects gaseous flow and cannot affect heavy particle motion.
  • 上空の乱流構造が都市キャニオン内のガス拡散に及ぼす影響, 道岡武信, 瀧本浩史, 佐藤歩, 日本機械学会流体工学部門講演会講演論文集(CD-ROM), 91st, ROMBUNNO.G0901,   2013 , http://jglobal.jst.go.jp/public/201402292650792931
  • Characterization of Long-Term Used De-NOx Catalyst, 丹野賢二, 野田直希, 山本融, 黒瀬良一, 道岡武信, 牧野尚夫, 粉体工学会誌, 50, 10, 733-740 (J-STAGE),   2013 , 10.4164/sptj.50.733, http://jglobal.jst.go.jp/public/201402233019640015
  • Effect of Particle Collision and Rebound Behavior on Adhesion Characteristics on the Wall of Honeycomb Shaped Catalyst, 丹野賢二, 黒瀬良一, 道岡武信, 牧野尚夫, 小森悟, 粉体工学会誌, 50, 3, 204-211 (J-STAGE),   2013 , 10.4164/sptj.50.204, http://jglobal.jst.go.jp/public/201302275264433073
  • Effect of Particle Collision and Rebound Behavior on Adhesion Characteristics on the Wall of Honeycomb Shaped Catalyst, 丹野 賢二, 黒瀬 良一, 道岡 武信, 粉体工学会誌, 50, 3, 204, 211,   2013 , 10.4164/sptj.50.204, http://ci.nii.ac.jp/naid/40019611390
  • Invation on turbulence and mean characteristics of canyon vortices in real urban canyons, Takeaki Katsuki, Ayumu Sato, Takenobu Michioka, Aya Hagishima, Journal of Environmental Engineering (Japan), 77, 789, 795,   2012 10 01 , 10.3130/aije.77.789, https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84877029007&origin=inward
    Summary:In previous study, wind tunnel experiment for a real apartment complex was conducted to confirm the reproducibility of flow fieldwith field measurement values. In this study, a wind tunnel experiment for the same complex was conducted to comprehend the behaviors of turbulence and mean characteristics of canyon vortices within real urban canyons. Mean flow field within the each canyon was the almost same flow motion which formed large canyon vortex. It was found that within the real canyon, the helical vortex generated by the flow from the side edge and the roof of the upstream building was formed. The detailed motion of the helical vortex is influenced by the building shapes, street width and positions of surrounding buildings.
  • Energy (Energy Conservation), MICHIOKA Takenobu, 化学工学 = Chemical engineering, 76, 5, 282, 283,   2012 05 05 , http://ci.nii.ac.jp/naid/10030595137
  • Study on wind attenuation effects of buildings array : Numerical analysis on applicable conditions of class-C wind load for electric power distribution facilities, 服部 康男, 道岡 武信, 佐藤 歩, 電力中央研究所報告. 研究報告. 電力中央研究所地球工学研究所 編, 11052, 1, 35,巻頭1-3,   2012 05 , http://ci.nii.ac.jp/naid/40019420717
  • Comparison between wind tunnel experiments and field measurement values on flow field in real Urban canyons, Takeaki Katsuki, Ayumu Sato, Takenobu Michioka, Aya Hagishima, Journal of Environmental Engineering, 77, 313, 319,   2012 04 01 , 10.3130/aije.77.313, https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84867277368&origin=inward
    Summary:Improvement of outdoor ventilated environment contributes notonlyto energy-saving and suppression of CO2 but also toindoorairqualityand itscomfort.Toconsider outdoor well-ventilatedenvironment, a flow field withinideal urbancanyons hasbeeninvestigated by wind tunnel experiment, but thebehaviorsof turbulence and mean characteristics ofcanyon vortices within real urbancanyons arestill not comprehended. In thisstudy, a wind tunnel experiment fora real apartmentcomplex wasconducted to confirm the reproducibility of flow field within the canyon. The apartment complex islocated at Musashino city,Tokyo, where fieldmeasurement was conducted.Thebuildings witha height more than two-stories were resolved within 200m radius under the modellength ratio of 1/150 was measured using both PIV (ParticleImageVelocimetry) and LDV (Laser Doppler Velocimeter). Thesemeasurements at5 points withinthe urban canyon werecompared with field measurement values. The wind velocities andturbulentintensitiesobtained by bothPIV and LDV fairly agreed withthe field measurement values withintheurban canyons, though a small-scale surface roughnesslike a balcony was notmodeled in the present wind tunnel experiment.
  • Evaluation of thermal and air environment in plant factory (Part. 1), 後藤 文之, 道岡 武信, 庄子 和博, 電力中央研究所報告. 研究報告. 電力中央研究所環境科学研究所 編, 11017, 1, 16,巻頭1-3,   2012 04 , http://ci.nii.ac.jp/naid/40019337203
  • COMPARISON BETWEEN WIND TUNNEL EXPERIMENTS AND FIELD MEASUREMENT VALUES ON FLOW FIELD IN REAL URBAN CANYONS : Wind tunnel experiments on flow field in real urban canyons (Part 1), 香月 壮亮, 佐藤 歩, 道岡 武信, 日本建築学会環境系論文集, 77, 674, 313, 319,   2012 04 , 10.3130/aije.77.313, http://ci.nii.ac.jp/naid/40019275173
  • Numerical simulations on thermal and wind environment in real urban canyons, 道岡 武信, 佐藤 歩, 香月 壮亮, 電力中央研究所報告. 研究報告. 電力中央研究所環境科学研究所 編, 11016, 1, 15,巻頭1-3,   2012 04 , http://ci.nii.ac.jp/naid/40019323787
  • Evaluation of thermal and air environment in plant factory (Part. 2) Numerical simulation for plant factory without vegetation, 道岡 武信, 佐藤 歩, 後藤 文之, 電力中央研究所報告. 研究報告. 電力中央研究所環境科学研究所 編, 11018, 1, 14,巻頭1-3,   2012 04 , http://ci.nii.ac.jp/naid/40019323812
  • Development of numerical model of stack gas diffusion under terrain condition : Applications of numerical model to high stacks, 佐田 幸一, 佐藤 歩, 道岡 武信, 大気環境学会誌 = Journal of Japan Society for Atmospheric Environment, 47, 6, 261, 269,   2012 , 10.11298/taiki.47.261, http://ci.nii.ac.jp/naid/40019505232
  • Wind tunnel experiments on flow field in real urban canyons, 香月 壮亮, 佐藤 歩, 道岡 武信, 電力中央研究所報告 研究報告, 10016, 1, 16,巻頭1〜3,   2011 05 , http://ci.nii.ac.jp/naid/40018879023
  • Practical capability of an atmospheric diffusion numerical model for safety analysis of nuclear facility: sensitivity analysis of a numerical model, 佐田 幸一, 道岡 武信, 佐藤 歩, 電力中央研究所報告 研究報告, 10009, 1, 33,巻頭1〜3,   2011 04 , http://ci.nii.ac.jp/naid/40018867792
  • Numerical simulations for airflow and thermal diffusion around apartment buildings, 道岡 武信, 佐藤 歩, 電力中央研究所報告 研究報告, 10001, 1, 15,巻頭1〜3,   2010 12 , http://ci.nii.ac.jp/naid/40017655471
  • Experimental validation for subgrid scale scalar variance model in a turbulent reacting liquid flows, Michioka Takenobu, Takagaki Naohisa, Kurose Ryoichi, Komori Satoru, Proceedings, ... meeting of Japan Society of Fluid Mechanics, 2010,   2010 09 09 , http://ci.nii.ac.jp/naid/110008460170
    Summary:The subgrid scale (SGS) variance for a high-Schmidt-number passive scalar of Sc>>1 is measured using a high-resolution planar laser-induced fluorescence (PLIF) technique in a grid-generated turbulent liquid flow, and the value of the model coefficient in the scale-similarity model used for estimating the SGS scalar variance is experimentally evaluated. The results show that the measured values of the model coefficient are much larger than the well-known values obtained in the previous studies done for non-high-Sc scalars of Sc&cong;1.
  • Wind tunnel experiments for simulating turbulent motions in a real atmospheric boundary layer, Takenobu Michioka, Ayumu Sato, Yasuo Hattori, Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B, 76, 823, 829,   2010 05 01 , 10.1299/kikaib.76.765_823, https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=77955194889&origin=inward
    Summary:A wind tunnel experiment was conducted to simulate large-scale turbulent motions in an atmospheric boundary layer (ABL). The large-scale turbulent motions originating from outer-layer disturbance were generated using an active grid installed at the front of the test section and the winglets of the active grid were randomly rotated. The large-scale horizontal motions in the ABL were generated in the wind tunnel using the active grid when appropriate values of the angle and rotation speed were chosen. The validity of the present method using the active grid was confirmed by comparing the integral scale and energy spectra obtained by the experiments with empirical formulas inferred from field observations. This indicates that the present method of using the active grid accurately simulates the turbulent motions in a nearly neutral ABL.
  • Development of CFD model considering mesoscale disturbance for gas dispersion in an urban district, 道岡 武信, 佐藤 歩, 佐田 幸一, 電力中央研究所報告 研究報告, 9024, 1, 21,巻頭1〜3,   2010 05 , http://ci.nii.ac.jp/naid/40017174949
  • Wind tunnel experiments for impacts of wall heating induced by solar radiation on the air flow and atmospheric dispersion within a street canyon, 佐藤 歩, 道岡 武信, 電力中央研究所報告 研究報告, 9017, 1, 23,巻頭1〜3,   2010 04 , http://ci.nii.ac.jp/naid/40017124709
  • Mechanisms of gas removal from a two-dimensional canyon using large-eddy simulations, Takenobu Michioka, Ayumu Sato, Hiroshi Takimoto, Manabu Kanda, HARMO 2010 - Proceedings of the 13th International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes, 789, 792,   2010 01 01 , https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84933509252&origin=inward
    Summary:This study focuses on the effect of turbulent organized structure (TOS) on pollutant removal from ideal street canyon. Large-eddy simulation (LES) is conducted to investigate the mechanism of pollutant removal from a two-dimensional canyon with a building-height-tostreet-width (aspect) ratio of 1.0. A tracer gas is released as a ground-level line source at the center of the canyon floor. The pollutant removal from the canyon is predominated not by advective flow, but by turbulent motion, except on the windward side of the canyon. The turbulent motion is derived from the TOS that appears close to the plane of the crest. When the TOS passes over the street canyon where the pollutant is retained, the pollutant is largely ejected from the street canyon. This indicates that the TOS has a strong influence on pollutant removal from a street canyon.
  • 1302 Numerical simulation of scalar dispersion in and above a canopy layer, MICHIOKA Takenobu, SATO Ayumu, Fluids engineering conference ..., 2009, 413, 414,   2009 11 06 , http://ci.nii.ac.jp/naid/110007861366
    Summary:Large-eddy simulation was conducted to investigate mechanism of gas exchange in and above a two-dimensional canopy layer. A tracer gas was released as a ground-level continuous gas line source at the center between blocks. The results show that a low-momentum region (LMR), defined as a region in the flow where instantaneous streamwise velocity is lower than the local mean velocity, was appeared as a turbulent organized structure above the canopy layer. The LMR has strongly influence on removal of gas from the street canyon to the free surface.
  • The visible plume model for a mechanical-draft cooling tower : Field campaign for visible plume measurements, Shimota Akiro, Michioka Takenobu, Sada Koichi, Sato Ayumu, Kanzaki Takao, Wada Koji, Ichikawa Yoichi, Journal of Japan Society for Atmospheric Environment, 44, 5, 255, 261,   2009 09 10 , 10.11298/taiki.44.255, http://ci.nii.ac.jp/naid/110007360871
    Summary:Recently, power plant's cooling towers equipped with instruments for preventing plume to visualize, which is a mechanical-draft cooling tower, tend to be planned and be constructed in Japan. Traditional ways of environmental assessment for a cooling tower has adopted a visible plume prediction model based on a natural-draft cooling tower. The requirement of developing new visible plume model having capability of prediction of visible plume, temperature, moisture and droplet from a mechanical-draft cooling tower is rising up. A field campaign to obtain data from a power plant with a mechanical-draft cooling tower for evaluation and validation of a new visible plume model and some conventional models is conducted. Measurements of surface temperature and humidity distribution around the plant does not show a clear effect of visible plume. Over 100 pairs of visible plume height and length are obtained by using video cameras and thermographyies Furthermore, droplet from the cooling tower shows very few amounts at a ground because of adopting to it a eliminator for preventing droplet scattering.
  • Visible plume model for a mechanical-draft cooling tower : Development of the visible plume model, Michioka Takenobu, Sato Ayumu, Shimota Akiro, Sada Koichi, Ichikawa Yoichi, Okura Arata, Journal of Japan Society for Atmospheric Environment, 44, 5, 227, 235,   2009 09 10 , 10.11298/taiki.44.227, http://ci.nii.ac.jp/naid/110007360879
    Summary:A new visible plume model is developed to predict visible plume, temperature, moisture and droplet from a mechanical-draft cooling tower. The developed model is a normal Gaussian plume model for moisture and temperature, considering fan configuration, wet-dry combined cooling tower system, vertical atmospheric temperature and atmospheric stability. The accuracy of previous models (FOG, SACTI) and the developed model is investigated to compare the model results with observation conducted in Japan. The results show that the previous models can not accurately predict the visible plume length and height because they have mainly developed for a natural-drift cooling tower, which is different type from a mechanical-draft cooling tower. On the other hand, the visible plume length and height predicted by the developed model are in good agreement with the observation, and statistical data analysis also shows that the model provides better performance than the previous models. Furthermore, the model predicts not only the visible plume region but also temperature, moisture and droplet from the cooling tower.
  • Large-Eddy Simulation of a Turbulent Reacting Liquid Flow : Application of Flamelet Model to LES, KOHNO Naoki, KUROSE Ryoichi, KOMORI Satoru, BABA Yuya, MICHIOKA Takenobu, Proceedings, ... meeting of Japan Society of Fluid Mechanics, 2009,   2009 09 02 , http://ci.nii.ac.jp/naid/110008459767
    Summary:Three-dimensional large-eddy simulations (LES) with flamelet models are applied to a grid-generated turbulent reacting liquid flow, and the predictions are compared with the experiments. A second-order, irreversible and isothermal reaction (A+B→2P) with rapid or moderately fast reaction is considered. The results show that the LES results based on flamelet models are in good agreement with the measurements both for the rapid and moderately fast reactions.
  • Wind tunnel experiment for gas dispersion in an atmospheric boundary layer, MICHIOKA Takenobu, SATO Ayumu, HATTORI Yasuo, Proceedings, ... meeting of Japan Society of Fluid Mechanics, 2009,   2009 09 02 , http://ci.nii.ac.jp/naid/110008459917
    Summary:A wind tunnel experiment was conducted to simulate larger-scale turbulent motion accompanying scalar transport and diffusion from a point source in an atmospheric boundary layer (ABL). To generate larger-scale turbulent motion, active grid was used in the present experiment. The lateral large-scale motion in ABL was generated in the wind tunnel using an active grid, when appropriate parameters of the angle and the rotated speed were chosen. In addition, it was found that the present method using active grid accurately simulates gas dispersion in a nearly neutral ABL.
  • 3D1040 Wind tunnel experiment of turbulence and atmospheric dispersion using an active grid : (1) Generation of large-scale turbulent motion(3 Method-5 simulation,General Presentations), MICHIOKA Takenobu, SATO Ayumu, KANZAKI Takao, SADA Koichi, 大気環境学会年会講演要旨集, 50,   2009 08 20 , http://ci.nii.ac.jp/naid/110007484069
  • 3D1052 Experimental and numerical simulation of pollutant dispersion in a high density residential area : (4) Influence of a turbulent Schmidt number in RANS on pollutant dispersion(3 Method-5 simulation,General Presentations), MICHIOKA Takenobu, SATO Ayumu, 大気環境学会年会講演要旨集, 50,   2009 08 20 , http://ci.nii.ac.jp/naid/110007484070
  • 3D1104 Experimental and numerical simulation of pollutant dispersion in a high density residential area : (5) -Airflow and pollutant dispersion behind a building under unstable stratification-(3 Method-5 simulation,General Presentations), SATO Ayumu, MICHIOKA Takenobu, 大気環境学会年会講演要旨集, 50,   2009 08 20 , http://ci.nii.ac.jp/naid/110007484071
  • 3D1116 Numerical model for stack gas diffusion under building and terrain conditions (6) : Variations in tracer gas diffusion with additional building(3 Method-5 simulation,General Presentations), SADA Koichi, MICHIOKA Takenobu, 大気環境学会年会講演要旨集, 50,   2009 08 20 , http://ci.nii.ac.jp/naid/110007484072
  • 3F1312 Field experiments of dispersion within street canyons of the comprehensive outdoor scale model (2) : Influences of horizontal flows on tracer gas concentration within the canyon(1 Space-2 roadside scale/4 Process -1 emission,General Presentations), SATO Ayumu, MICHIOKA Takenobu, 大気環境学会年会講演要旨集, 50,   2009 08 20 , http://ci.nii.ac.jp/naid/110007484154
  • 322 Large-eddy simulation of gas dispersion in an urban district, MICHIOKA Takenobu, SATO Ayumu, Symposium on Environmental Engineering, 2009, 19, 325, 326,   2009 07 08 , http://ci.nii.ac.jp/naid/110008009234
    Summary:The performance of large-eddy simulation (LES) for gas dispersion in an urban district is investigated. The present simulation is based on a finite volume method with an unstructured grid system to resolve flow structure in a complex geometry. To evaluate the performance of the LES, the results from the LES are compared with those obtained by the wind tunnel experiments, which were conducted for gas dispersion from a point source at the roof of a tall building in a complex urban district. The result shows that the LES can accurately represent the flow and concentration field provided that suitable numerical schemes are used.
  • 323 A study of airflow and atmospheric dispersion in arrays of urban buildings, SATO Ayumu, MICHIOKA Takenobu, TAKIMOTO Hiroshi, Symposium on Environmental Engineering, 2009, 19, 327, 328,   2009 07 08 , http://ci.nii.ac.jp/naid/110008009235
  • Wind tunnel experiments on airflow and thermal diffusion around apartment buildings, 佐藤 歩, 道岡 武信, 田中 伸幸, 電力中央研究所報告 研究報告, 8055, 1, 18,巻頭1〜3,   2009 07 , http://ci.nii.ac.jp/naid/40016795154
  • Numerical Model for Atmospheric Diffusion Analysis and Evaluation of Effective Dose for Safety Analysis : Effective Stack Height and Effective Dose Estimated by Wind Tunnel and Numerical Model, SADA Koichi, KOMIYAMA Sumito, MICHIOKA Takenobu, ICHIKAWA Yoichi, Journal of the Atomic Energy Society of Japan / Atomic Energy Society of Japan, 8, 2, 184, 196,   2009 06 01 , 10.3327/taesj.J08.043, http://ci.nii.ac.jp/naid/10024978120
    Summary:A numerical simulation method has been developed to predict atmospheric flow and stack gas diffusion, considering the buildings and complex terrain located near and relatively far from a stack, respectively. The turbulence closure technique was used for flow calculation, some calculation grids on the ground near a stack were treated as buildings, and stack gas diffusion was predicted using the Lagrangian particle model. The calculated flow and stack gas diffusion results were compared with those obtained by wind tunnel experiments under actual terrain containing buildings. Effective stack height was estimated by comparing the surface concentration along the plume axis with those under a flat-plate condition, and it was apparent that the effective stack heights estimated by calculations were almost the same as those obtained by the wind tunnel experiment. Then, the effective dose and relative concentration of stack gas were calculated using the effective stack heights obtained by a numerical model. Almost the same effective dose and relative concentration were obtained when compared with those using the effective stack height obtained by wind tunnel experiment.
  • Visible plume model for a mechanical-draft cooling tower : Development of the plume height and diffusion models, Michioka Takenobu, Sato Ayumu, Sada Koichi, Shimota Akiro, Ichikawa Yoichi, Journal of Japan Society for Atmospheric Environment, 44, 3, 147, 154,   2009 05 10 , 10.11298/taiki.44.147, http://ci.nii.ac.jp/naid/110007227698
    Summary:We developed new plume rise and diffusion models for gas dispersion from a mechanical-draft cooling tower. Wind tunnel experiments were conducted to investigate effects of fan location and cooling tower configuration on gas dispersion from the cooling towers. The results show that cooling tower configuration does not affect the plume rise and diffusion, but the fan location and numbers strongly affect them. The plume rise increases with the fun number in case of the fans located in downwind direction, but it is comparable level to the single fan in case of orthogonally-aligned fans to the wind direction. In addition, the vertical and horizontal diffusion becomes large as the fan number increases. These effects are not considered by the previous Gaussian type model (FOG model), generating the large difference of the plume rise and dispersion between the model and the wind tunnel experiment. On the other hand, the developed models considering the fan location and number can accurately estimate the plume rise and diffusion from the mechanical-draft cooling towers.
  • The numerical model for atmospheric diffusion and evaluation of effective dose for safety analysis: the effective stack height and effective dose estimated by wind tunnel and numerical model, 佐田 幸一, 道岡 武信, 市川 陽一, 電力中央研究所報告 研究報告, 8046, 1, 27,巻頭1〜3,   2009 05 , http://ci.nii.ac.jp/naid/40016714767
  • Development of prediction method for a visible plume from a mechanical draft-cooling tower (2nd report, numerical simulation to predict a visible plume), Takenobu Michioka, Ayumu Sato, Koichi Sada, Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B, 75, 604, 611,   2009 04 01 , 10.1299/kikaib.75.752_604, https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=67650627793&origin=inward
    Summary:A Large eddy simulation (LES) was developed to predict a visible plume region from a mechanical -draft cooling tower. This numerical model solves the equations for conservation of mass, momentum, energy, vapor and liquid water. Itis assumed that the visible plume is generated whenever the instantaneous liquid water mixing ratio is existed. To estimate the accuracy of the present numerical model, the predictions of visible plume length and height are compared with observations. The results show the visible plume length and height are in good agreement with the observations. Furthermore, we investigate the basic behavior of the visible plume and temperature emitted from the cooling tower under severe metrological condition. It is found that whether the visible plume reaches the ground or not mostly depends on the wind angle to the cooling tower, and temperature emitted from the cooling tower has little influence on atmosphere environment on the ground.
  • Numerical simulations of gas dispersion in an urban district: estimation of numerical simulations using wind tunnel experiments, 道岡 武信, 佐藤 歩, 電力中央研究所報告 研究報告, 8030, 1, 33,巻頭1〜3,   2009 04 , http://ci.nii.ac.jp/naid/40016672919
  • Field and wind tunnel experiments about flow and dispersion within an urban canyon, 佐藤 歩, 道岡 武信, 瀧本 浩史, 電力中央研究所報告 研究報告, 8027, 1, 19,巻頭1〜3,   2009 04 , http://ci.nii.ac.jp/naid/40016714761
  • Development of prediction method for a visible plume from a mechanical draft-cooling tower (1st report, wind tunnel experiments to predict a visible plume), Takenobu Michioka, Ayumu Sato, Koichi Sada, Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B, 75, 93, 100,   2009 01 01 , 10.1299/kikaib.75.749_93, https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=63849260747&origin=inward
    Summary:We developed a method for a wind tunnel experiment to predict a visible plume region from a mechanical draft cooling tower. The diffusions of water vapor and temperature emitted from the cooling tower in the wind tunnel experiment are tracked using tracer gas. It is assumed that the plume-induced fog is generated whenever the instantaneous specific humidity predicted from the concentration of the tracer gas at measuring points is larger than the inferred saturation specific humidity. To estimate the accuracy of the present method, the measurements are compared with the observations. The results show that the visible plume length and height are in good agreement with the observations. Furthermore, it is found that the visible length and height is strongly affected by wind direction to the cooling tower, temperature difference between atmosphere and exit of the cooling tower and atmospheric humidity, and hence the present wind tunnel method considered these conditions is valid to predict the visible plume.
  • Numerical model for stack gas diffusion in terrain with buildings-variations in air flow and gas concentration with additional building near stack-, Koichi Sada, Sumito Komiyama, Kunio Numata, Takenobu Michioka, Yoichi Ichikawa, International Congress on Advances in Nuclear Power Plants 2009, ICAPP 2009, 2, 1293, 1302,   2009 01 01 , https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84908000850&origin=inward
    Summary:A numerical simulation method for predicting atmospheric flow and stack gas diffusion using a calculation domain of several km around a stack under complex terrain conditions containing buildings has been developed. The turbulence closure technique using a modified k-ε-type model without a hydrostatic approximation was used for flow calculation, and some of the calculation grids near the ground were treated as buildings using a terrain-following coordinate system. Stack gas diffusion was predicted using the Lagrangian particle model, that is, the stack gas was represented by trajectories of released particles. The developed numerical model was applied to a virtual terrain and building conditions in this study prior to the applications of a numerical model for real terrain and building conditions. The height of the additional building (Ha) located about 200m leeward from the stack, was varied (i.e., Ha=0, 20, 30 and 50m), and its effects on airflow and the concentration of stack gas at a released height of 75m were calculated. Furthermore, effective stack height, which was used in the safety analysis of atmospheric diffusion for nuclear facilities in Japan, was evaluated from the calculated ground-level concentration of stack gas. The cavity region behind the additional building was calculated, and turbulence near the cavity was observed to decrease when the additional building was present. According to these flow variations with the additional building, tracer gas tended to diffuse to the ground surface rapidly with the additional building at the leeward position of the cavity, and the ground-level stack gas concentration along the plume axis also increased with the height of the additional building. However, the variations in effective stack height with the height of the additional building were relatively small and ranged within several m in this study.
  • High-resolution large-eddy simulations of scalar transport in atmospheric boundary layer flow over complex terrain, Takenobu Michioka, Fotini Katopodes Chow, Journal of Applied Meteorology and Climatology, 47, 3150, 3169,   2008 12 01 , 10.1175/2008JAMC1941.1, https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=65249121506&origin=inward
    Summary:This paper presents high-resolution numerical simulations of the atmospheric flow and concentration fields accompanying scalar transport and diffusion from a point source in complex terrain. Scalar dispersion is affected not only by mean flow, but also by turbulent fluxes that affect scalar mixing, meaning that predictions of scalar transport require greater attention to the choice of numerical simulation parameters than is typically needed for mean wind field predictions. Large-eddy simulation is used in a mesoscale setting, providing modeling advantages through the use of robust turbulence models combined with the influence of synoptic flow forcing and heterogeneous land surface forcing. An Eulerian model for scalar transport and diffusion is implemented in the Advanced Regional Prediction System mesoscale code to compare scalar concentrations with data collected during field experiments conducted at Mount Tsukuba, Japan, in 1989. The simulations use horizontal grid resolution as fine as 25 m with up to eight grid nesting levels to incorporate time-dependent meteorological forcing. The results show that simulated ground concentration values contain significant errors relative to measured values because the mesoscale wind typically contains a wind direction bias of a few dozen degrees. Comparisons of simulation results with observations of arc maximum concentrations, however, lie within acceptable error bounds. In addition, this paper investigates the effects on scalar dispersion of computational mixing and lateral boundary conditions, which have received little attention in the literature - in particular, for high-resolution applications. The choice of lateral boundary condition update interval is found not to affect time-averaged quantities but to affect the scalar transport strongly. More frequent updates improve the simulated ground concentration values. In addition, results show that the computational mixing coefficient must be set to as small a value as possible to improve scalar dispersion predictions. The predicted concentration fields are compared as the horizontal grid resolution is increased from 190 m to as fine as 25 m. The difference observed in the results at these levels of grid refinement is found to be small relative to the effects of computational mixing and lateral boundary updates. © 2008 American Meteorological Society.
  • Development of atmospheric turbulence and dispersion controlled method in wind tunnel experiment using active grids, 道岡 武信, 佐藤 歩, 服部 康男, 電力中央研究所報告 研究報告, 8005, 1, 15,巻頭1〜3,   2008 12 , http://ci.nii.ac.jp/naid/40016455265
  • Numerical Simulation of Scalar transport over complex terrain, Michioka Takenobu, Chow Fotini K, Proceedings, ... meeting of Japan Society of Fluid Mechanics, 2008,   2008 09 04 , http://ci.nii.ac.jp/naid/110008459542
    Summary:An atmospheric large-eddy simulation code has been applied to simulate scalar transport and dispersion from point source releases during a field campaign conducted near Mt. Tsukuba, Japan. The simulations use horizontal grid resolution as fine as 190m with six grid nesting levels to incorporate time-dependent meteorological forcing. The results show that predicted ground concentration values contain significant errors compared to measured values because the mesoscale wind typically contains a wind direction bias of a few dozen degrees. Comparisons of simulation results with observations of arc maximum concentrations, however, lie within acceptable error bounds.
  • An investigation of subgrid-scale models for turbulence and scalar transport over a steep hill, Hino Yuta, Tamura Tetsuro, Michioka Takenobu, Proceedings, ... meeting of Japan Society of Fluid Mechanics, 2008,   2008 09 04 , http://ci.nii.ac.jp/naid/110008459637
    Summary:This paper performs LES of velocity and concentration over a steep hill. Under this condition, a priori test illustrate that eddy viscosity models, Smagorinsky model(SM), Dynamic Smagorinsky model(DSM), cannot completely represent the SGS stress terms, while Dynamic Mixed model (DMM) can. Velocities calculated by LES with DMM match experimental data in front of and near the hill better than other SGS models. Concentration also match experimental data at the top of the hill because of reproduction of velocity profiles in front of the hill.
  • 1E0930 Development of Visible Plume Evaluation Method from Cooling Tower of Power Plant (1) : Field Observation of Visible plume(2 Method-5 simulation,General Presentations), SADA Koichi, MICHIOKA Takenobu, SATO Ayumu, SHIMODA Akio, ICHIKAWA Yoichi, 大気環境学会年会講演要旨集, 49,   2008 08 29 , http://ci.nii.ac.jp/naid/110007075758
  • 1E0954 Numerical Model for Stack Gas Diffusion under Building and Terrain Conditions (5) : Surface Concentration Profile along Plume Axis(2 Method-5 simulation,General Presentations), SADA Koichi, MICHIOKA Takenobu, ICHIKAWA Yoichi, 大気環境学会年会講演要旨集, 49,   2008 08 29 , http://ci.nii.ac.jp/naid/110007075759
  • 1E1030 Experimental and numerical simulation of pollutant dispersion in a high density residential area (No. 3) : LES simulation of pollutant dispersion(2 Method-5 simulation,General Presentations), MICHIOKA Takenobu, SATO Ayumu, 大気環境学会年会講演要旨集, 49,   2008 08 29 , http://ci.nii.ac.jp/naid/110007075760
  • 1E1018 Experimental and numerical simulation of pollutant dispersion in a high density residential area : (2) RANS simulation of pollutant dispersion(2 Method-5 simulation,General Presentations), SATO Ayumu, MICHIOKA Takenobu, 大気環境学会年会講演要旨集, 49,   2008 08 29 , http://ci.nii.ac.jp/naid/110007075898
  • 1E0942 Development of Visible Plume Evaluation Method from Cooling Tower of Power Plant (2) : Development of visible plume model(2 Method-5 simulation,General Presentations), MICHIOKA Takenobu, SATO Ayumu, SADA Koichi, SHIMODA Akio, ICHIKAWA Yoichi, 大気環境学会年会講演要旨集, 49,   2008 08 29 , http://ci.nii.ac.jp/naid/110007076031
  • 1D1118 Field experiments of dispersion within street canyons of the Comprehensive Outdoor Scale Model(1 Space-2 roadside scale,General Presentations), SATO Ayumu, MICHIOKA Takenobu, 大気環境学会年会講演要旨集, 49,   2008 08 29 , http://ci.nii.ac.jp/naid/110007076033
  • 2506 Particle diffusion in a particle-laden swirling jet, MICHIOKA Takenobu, KUROSE Ryoichi, The Computational Mechanics Conference, 2007, 20, 89, 90,   2007 11 25 , http://ci.nii.ac.jp/naid/110007084685
  • Effect of Flow Behavior in De-NO_x Catalyst Honeycomb on Adhesion of Particles to the Wall, KUROSE Ryoichi, MICHIOKA Takenobu, MAKINO Hisao, KOMORI Satoru, Journal of the Society of Powder Technology,Japan, 44, 2, 107, 112,   2007 02 10 , 10.4164/sptj.44.107, http://ci.nii.ac.jp/naid/10018506802
  • Large-Eddy Simulation of Particle Diffusion in a Particle-laden Swirling Jet(Fluid Engineering), MICHIOKA Takenobu, KUROSE Ryoichi, Transactions of the Japan Society of Mechanical Engineers. B, 73, 725, 30, 37,   2007 01 25 , 10.1299/kikaib.73.30, http://ci.nii.ac.jp/naid/110006165251
    Summary:Three-dimensional large-eddy simulation (LES) is applied to a particle-laden swirling jet, and the effect of swirl on particle diffusion is investigated. The trajectories of all particles are individually pursued with a Lagrangian method. The particles with different diameters are uniformly injected into the non-swirling and swirling flows with different Swirling numbers. The result shows that the trajectories of the particles with different diameters are quite different. The smaller particles have the peak of the particle number densities at central axis, and diffuse across swirling jet. On the other hand, the larger particles at the exit of the nozzle migrate outward by the centrifugal force, but the particles gradually migrate inward with the axial distance increases. The inward movement of the particle in the downstream region is dominated by turbulent motions, which transport the particles inward near central axis. Furthermore, above behavior is shifted upstream with the particle diameter decrease because the smaller particles are easily transferred by smaller inward fluid motions existing in the wide range of the swirling jet.
  • AM06-02-001 Large-Eddy Simulation for visible plume from a mechanical draft cooling tower, Michioka Takenobu, Sada Kouichi, Proceedings, ... meeting of Japan Society of Fluid Mechanics, 2006,   2006 09 05 , http://ci.nii.ac.jp/naid/110008458657
    Summary:A Large-Eddy Simulation (LES) was developed to predict a visible plume region from a mechanical-draft cooling tower. This numerical model solves the equations for conservation of mass, momentum, energy, vapor and liquid water. It is assumed that the visible plume is generated whenever the instantaneous liquid water mixing ratio is existed. To estimate the accuracy of the present numerical model, the predictions of visible plume length and height are compared with observations in real cooling tower. The results show that the visible plume length and height are nearly in agreement with the observations and the present numerical model has capability to predict the visible plume region from the cooling tower.
  • AM06-13-016 Numerical Model for Stack Gas Diffusion under Building and Terrain Conditions : Application of Numerical Model for Simple Building and Ridge Conditions, Sada Koichi, Michioka Takenobu, Ichikawa Yoichi, Proceedings, ... meeting of Japan Society of Fluid Mechanics, 2006,   2006 09 05 , http://ci.nii.ac.jp/naid/110008458791
    Summary:A numerical simulation method has been developed to predict atmospheric flow and stack gas diffusion under the buildings and complex terrain conditions. The turbulence closure technique was used for flow calculation, some calculation grids on the ground within a plant area were treated as buildings under the terrain following coordinate, and stack gas diffusion was predicted using the Lagrangian particle model. The numerical model have been applied for the flow and stack gas diffusion around cubical building and two dimensional ridge terrain conditions in this report. Then, the calculated flow and stack gas diffusion results were compared with those obtained by wind tunnel experiments, and the features of flow and tracer gas diffusion, such as the increment of turbulent kinetic energy and plume spreads of stack gas behind the buildings and terrain, were reproduced by both calculations and wind tunnel experiments.
  • Numerical simulation of atmospheric flow and stack gas diffusion under building and complex terrain conditions: (Estimations of effective stack height and comparisons with wind tunnel experiments), Koichi Sada, Takenobu Michioka, Yoichi Ichikawa, JSME International Journal, Series B: Fluids and Thermal Engineering, 49, 48, 59,   2006 08 15 , 10.1299/jsmeb.49.48, https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=33747698422&origin=inward
    Summary:A numerical simulation method has been developed to predict atmospheric flow and stack gas diffusion under a neutral stratification condition, considering the buildings and complex terrain located near and relatively far from a stack, respectively. The turbulence closure technique was used for flow calculation, some calculation grids on the ground within a plant area were treated as buildings, and stack gas diffusion was predicted using the Lagrangian particle model. The calculated flow and stack gas diffusion results were compared with those obtained by wind tunnel experiments under a neutral stratification condition, and the features of surface concentration, such as the occurrence of downdraft phenomena behind the buildings, were reproduced by both calculations and wind tunnel experiments. Furthermore, effective stack heights were estimated by the comparison of the surface concentration along the plume axis with those under a flat-plate condition, and it was apparent that the effective stack heights estimated by calculations were almost the same as those obtained by wind tunnel experiments. Copyright © 2006 by The Japan Society of Mechanical Engineers.
  • Effects of Particles on Flows on Two-Phase Flows, MICHIOKA Takenobu, KUROSE Ryoichi, Atomization, 14, 48, 82, 91,   2005 12 31 , http://ci.nii.ac.jp/naid/10016734551
  • Effects of particles on turbulence and scalar diffusion of chemical species in a particle-laden maixing layer, Michioka Takenobu, Kurose Ryoichi, SADA Kouichi, Makino hisao, Fluids engineering conference ..., 2004,   2004 11 24 , http://ci.nii.ac.jp/naid/110004070855
  • Towards High Precision Predictions of Reactive-Diffusive Phenomena in Turbulent Liquid Flows(Mixing and Diffusion in Turbulence), KOMORI Satoru, MICHIOKA Takenobu, Journal of Japan Society of Fluid Mechanics, 23, 3, 149, 158,   2004 06 25 , 10.11426/nagare1982.23.149, http://ci.nii.ac.jp/naid/110003890160
  • Effects of Loaded Particles on Turbulence and Scalar Diffusion in a Mixing Layer, MICHIOKA Takenobu, KUROSE Ryoichi, SADA Kouichi, MAKINO Hisao, Transactions of the Japan Society of Mechanical Engineers. B, 69, 688, 2633, 2640,   2003 12 25 , 10.1299/kikaib.69.2633, http://ci.nii.ac.jp/naid/110002388435
    Summary:A direct numerical simulation (DNS) based on a finite volume method is applied to a particle-laden turbulent mixing layer in order to examine effects of loaded particles on turbulence and scalar diffusion. Trajectories of all particles are individually pursued with a Lagrangian method. The results show that the small particles, whose response time, τ_p, is smaller than the Kolmogorov time scale, τ_k, reduce the turbulent intensities of streamwise and transverse velocity fluctuations upstream of the mixing layer. However, the streamwise slope of turbulent intensities becomes high as compared to particle-free flow downstream of the mixing layer. Because source terms, which are energy exchange and turbulent production terms for the turbulent intensity of streamwise velocity fluctuation and pressure strain correlation term for that of transverse velocity fluctuation, are increased. Furthermore, the small particles increase the mean squared values of the concentration fluctuations.
  • Effects of Loaded Particles on Turbulence and Scalar Diffusion in a Mixing Layer, Takenobu Michioka, Ryoichi Kurose, Kouichi Sada, Hisao Makino, Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B, 69, 2633, 2640,   2003 12 01 , 10.1299/kikaib.69.2633, https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=1442314742&origin=inward
    Summary:A direct numerical simulation (DNS) based on a finite volume method is applied to a particle-laden turbulent mixing layer in order to examine effects of loaded particles on turbulence and scalar diffusion. Trajectories of all particles are individually pursued with a Lagrangian method. The results show that the small particles, whose response time, τp, is smaller than the Kolmogorov time scale, τ k, reduce the turbulent intensities of streamvrise and transverse velocity fluctuations upstream of the mixing layer. However, the streamwise slope of turbulent intensities becomes high as compared to particle-free flow downstream of the mixing layer. Because source terms, which are energy exchange and turbulent production terms for the turbulent intensity of streamwise velocity fluctuation and pressure strain correlation term for that of transverse velocity fluctuation, are increased. Furthermore, the small particles increase the mean squared values of the concentration fluctuations.
  • Wind Tunnel Experiment of Tracer Gas Concentration Fluctuation in Atmospheric Turbulent Boundary Layer : Effects of Averaging Time on Concentration Fluctuation Characteristics, SADA Koichi, SATO Ayumu, MICHIOKA Takenobu, Procee[d]ings of Thermal Engineering Conference, 2003, 43, 44,   2003 11 10 , http://ci.nii.ac.jp/naid/110002489416
    Summary:The concentration fluctuation of tracer gas emitted from an elevated point source within the atmospheric turbulent boundary layer was simulated and measured in a wind-tunnel experiment, and the concentration fluctuation of tracer gas was measured using a fast-response flame ionization detector. The effects caused by the averaging time to concentration fluctuation characteristics were analyzed in this study. The variations with the averaging time for the ratios of peak concentration to mean values showed almost similar profiles as those obtained in atmosphere. Furthermore, the relations between the skewness and flatness factors of were also observed for concentration fluctuation measured in wind tunnel.
  • Effects of laden particles in two-phase flows on turbulence and scalar diffusion of chemical species, MICHIOKA Takenobu, KUROSE Ryoichi, SADA Kouichi, MAKINO Hisao, Procee[d]ings of Thermal Engineering Conference, 2003, 231, 232,   2003 11 10 , http://ci.nii.ac.jp/naid/110002489625
    Summary:A direct numerical simulation (DNS) is applied to a particle-laden turbulent mixing layer with a chemical reaction, and the effects of particles on turbulence and chemical species' diffusion and reaction are investigated. The unreactive particles, whose response time, τ_P, is smaller than the Kolmogorov time scale, τ_K, [τ_P/τ_K=O(10-1)], are uniformly injected into the high-speed side of the mixing layer. Two reactive chemical species are separately introduced through different sides. The results show that although laden particles generally depress the streamwise and transverse turbulent intensities and mean squared value of concentration fluctuation on the central interface in the mixing layer, they begin to enhance them downstream as the particle size decreases provided the inlet particle volume fraction is fixed. Also, since the small-scale turbulence in the coherent vortices, which promotes the chemical reaction, are suppressed by the laden particles in he whole region, chemical product decreases overall.
  • Effects of particles on turbulence and scalar diffusion in a particle-laden mixing layer, MICHIOKA Takenobu, KUROSE Ryoichi, SADA Kouichi, MAKINO Hisao, Fluids engineering conference ..., 2003,   2003 09 18 , http://ci.nii.ac.jp/naid/110002510000
  • Large-Eddy Simulation for the Tracer Gas Concentrration Fluctuation in Atomospheric Boundary Layer, MICHIOKA Takenobu, SATO Ayumu, SADA Kouichi, Transactions of the Japan Society of Mechanical Engineers. B, 69, 680, 868, 875,   2003 04 25 , 10.1299/kikaib.69.868, http://ci.nii.ac.jp/naid/110002387997
    Summary:A Large-Eddy Simulation (LES) based on a finite-difference scheme is applied to stack gas diffusion of a turbulent boundary layer. A Flux-Corrected Transport (FCT) scheme is used to prevent a numerical oscillation and a negative concentration in the LES. Furthermore, a beta-Probability Density Function (PDF) model, which considers a Subgird Scale (SGS) concentration fluctuation, is applied to predict the detailed concentration statistics such as an instantaneous high concentration and an intermittency factor of the concentration in a coarse grid resolution. The validity of these methods is confirmed to compare the results of the LES with the wind tunnel measurements. The results show the predictions of the mean concentration and mean squared concentration fluctuation are in good agreement with the measurement and the present LES using the FCT scheme is applicable to the stack gas diffusion. The present method, which takes account of the concentration fluctuation, can exactly predict the instantaneous high concentration value and intermittent factor even in the coarse grid resolution.
  • Large-eddy simulation for the tracer gas concentration fluctuation in atmospheric boundary layer, Takenobu Michioka, Ayumu Sato, Kouichi Sada, Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B, 69, 868, 875,   2003 04 01 , 10.1299/kikaib.69.868, https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=0038346434&origin=inward
    Summary:A Large-Eddy Simulation (LES) based on a finite-difference scheme is applied to stack gas diffusion of a turbulent boundary layer. A Flux-Corrected Transport (FCT) scheme is used to prevent a numerical oscillation and a negative concentration in the LES. Furthermore, a beta-Probability Density Function (PDF) model, which considers a Subgird Scale (SGS) concentration fluctuation, is applied to predict the detailed concentration statistics such as an instantaneous high concentration and an intermittency factor of the concentration in a coarse grid resolution. The validity of these methods is confirmed to compare the results of the LES with the wind tunnel measurements. The results show the predictions of the mean concentration and mean squared concentration fluctuation are in good agreement with the measurement and the present LES using the FCT scheme is applicable to the stack gas diffusion. The present method, which takes account of the concentration fluctuation, can exactly predict the instantaneous high concentration value and intermittent factor even in the coarse grid resolution.
  • Effects of Thermal Stratifications on Turbulent Mixing and Chemical Reaction in Liquid Mixing Layer, ONISHI Ryo, MICHIOKA Takenobu, NAGATA Koji, KOMORI Satoru, Transactions of the Japan Society of Mechanical Engineers. B, 69, 679, 636, 643,   2003 03 25 , 10.1299/kikaib.69.636, http://ci.nii.ac.jp/naid/110002387933
    Summary:The effects of thermal stratifications on turbulent mixing and chemical reaction in the liquid mixing layer were investigated by both laboratory experiments and numerical simulations. The experiments were conducted in neutrally, unstably and stably stratified water flows with a rapid chemical reaction. Instantaneous velocities and concentration were simultaneously measured using a combined technique with a two component laser-Doppler velocimeter (LDV) and a later-induced fluorescence (LIF) method. Turbulence quantities such as the mean concentration of chemical product and turbulent mass fluxes were estimated and the effects of thermal stratifications on the quantities were clarified. Further, the large-eddy simulation (LES) using the large-eddy probability-density function (LEPDF) model as a SGS model was applied to the thermally-stratified reacting liquid flows. The results show that the effects of the stratifications on the turbulent mixing and chemical reaction can be well explained by the LES.
  • Effects of thermal stratifications on turbulent mixing and chemical reaction in liquid mixing layer, Ryo Onishi, Takenobu Michioka, Kouji Nagata, Satoru Komori, Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B, 69, 636, 643,   2003 03 01 , 10.1299/kikaib.69.636, https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=0037603642&origin=inward
    Summary:The effects of thermal stratifications on turbulent mixing and chemical reaction in the liquid mixing layer were investigated by both laboratory experiments and numerical simulations. The experiments were conducted in neutrally, unstably and stably stratified water flows with a rapid chemical reaction. Instantaneous velocities and concentration were simultaneously measured using a combined technique with a two component laser-Doppler velocimeter (LDV) and a later-induced fluorescence (LIF) method. Turbulence quantities such as the mean concentration of chemical product and turbulent mass fluxes were estimated and the effects of thermal stratifications on the quantities were clarified. Further, the large-eddy simulation (LES) using the large-eddy probabil- ity-density function (LEPDF) model as a SGS model was applied to the thermally-stratified reacting liquid flows. The results show that the effects of the stratifications on the turbulent mixing and chemical reaction can be well explained by the LES.
  • LES for predicting the instantaneous high concentration in an atmospheric boundary layer, Michioka Takenobu, Sato Ayumu, Sada Kouichi, 大気環境学会年会講演要旨集, 44,   2003 , http://ci.nii.ac.jp/naid/110003724038
  • Application of LES to Turbulent Liquid Flows with Chemical Reactions, ONISHI Ryo, MICHIOKA Takenobu, NAGATA Kouji, KOMORI Satoru, 熱工学講演会講演論文集, 2002, 23, 24,   2002 11 06 , http://ci.nii.ac.jp/naid/110002527826
    Summary:A Large-Eddy Simulation (LES) based on a finite volume method was appliedto turbulent liquid flows with moderately fast and rapid chemical reactions. The large-eddy probability density function (LEPDF) model and joint LEPDF model were used as a SGS model for a rapid reaction and for a moderately fast reaction, respectively. To investigate the applicability of the LES based on the proposed SGS models to neutrally, stably and unstably stratified reacting liquid flows, the results of the LES were compared with the measurements. The predictions of the LES were in good agreement with the measurements. The results also show that the present LES can accurately estimate the concentration statistics in neutrally, stably and unstably stratified liquid flows with reactions.
  • LES of the tracer gas concentration fluctuation in atmospheric boundary layer, MICHIOKA Takenobu, STATO Ayumu, SADA Kouichi, Proceedings, ... meeting of Japan Society of Fluid Mechanics, 2002, 250, 251,   2002 07 23 , http://ci.nii.ac.jp/naid/110003948075
    Summary:A Large-Eddy Simulation (LES) based on a finite-difference scheme is applied to stack gas diffusion of a turbulent boundary layer. A beta-Probability Density Function (PDF) model, which considers a Subgird Scale (SGS) concentration fluctuation, is applied to predict instantaneous high concentration in a coarse grid resolution. The validity of the method is confirmed to compare the results of the LES with the wind tunnel measurements. The results show that the present method, which takes account of the concentration fluctuation, can exactly predict the instantaneous high concentration value even in the coarse grid resolution.
  • Numerical Simulation of Tracer Gas Concentration Fluctuation around a Cubical Building : Eddy Scale of Concentration Fluctuation, SADA Kouichi, SATO Ayumu, MICHIOKA Takenobu, Proceedings, ... meeting of Japan Society of Fluid Mechanics, 2002, 252, 253,   2002 07 23 , http://ci.nii.ac.jp/naid/110003948076
    Summary:Tracer gas diffusion around a cubical building was estimated by using flow calculation results of large eddy simulation (LES) method. The concentration fluctuation was predicted both using finite difference method, in which the LES is expanded for concentration, and the puff method, in which small volumes of the tracer gas are divided and combined according to the calculation mesh sizes. In order to avoid numerical viscous effects, the puff method and finite difference method were applied in the regions near to and far from the tracer gas release point, respectively. The high concentration values and eddy scale of concentration fluctuation around a cubical building were estimated from concentration calculation results. Though the finite difference method were suitable for predicting the integral timo seale, its method overestimated the high values of concentration fluctuation.
  • K-1414 Large-eddy simulation for a liquid mixing layer, ONISHI Ryo, MICHIOKA Takenobu, NAGATA Kouji, KOMORI Satoru, 年次大会講演論文集 : JSME annual meeting, 0, 1, 231, 232,   2001 08 22 , http://ci.nii.ac.jp/naid/110002526602
    Summary:A large-eddy simulation (LES) based on a finite volume method was applied to a liquid turbulent flow with a rapid chemical reaction. The large eddy probability density function model was used as a subgrid-scale (SGS) model for a rapid reaction. The correlation coefficient in the scale similarity model between the variance of SGS concentration and that of test-filtered concentration was determined using the data of the DNS of liquid isotropic turbulence. To investigate the applicability of the LES to reacting liquid flows, both measurement and LES were performed in a liquid mixing layer with a rapid reaction. The prediction of the LES was in good agreement with the measurement. And the result also showed that the present LES can accurately estimate the concentration statistics in reacting liquid flows.
  • K-1415 Large Eddy Simulation of Reacting Turbulent Mixing Layer : Effects of Heat Release and Fluid Shear, KUROSE Ryoichi, MAKINO Hisao, MICHIOKA Takenobu, KOMORI Satoru, 年次大会講演論文集 : JSME annual meeting, 0, 1, 233, 234,   2001 08 22 , http://ci.nii.ac.jp/naid/110002526603
    Summary:Effects of the heat release and the fluid shear on the nonpremixed reaction processes are studied by applying a three-dimensional large eddy simulation (LES) to a compressible, spatially developing nonpremixed reacting plane mixing layer. The fluid shear is generated by the streamwise and spanwise inlet velocity differences between the fuel and oxidizer. SGS turbulence and combustion models used are the dynamic Smagorinsky model (DSM) and the scale similarity filtered reaction rate model (SSFRRM), respectively. The results show that the heat release and the spanwise fluid shear promote the mixing between the fuel and oxidizer and increase the production. Although Reynolds stress and fuel flux are usually positive in the isothermal mixing layer except, for the region near the inlet, these values become negative in certain regions away from the inlet due to the heat release and the spanwise fluid shear.
  • LES of Liquid Turbulent Flows with Chemical Reactions, ONISHI Ryo, MICHIOKA Takenobu, NAGATA Kouji, KOMORI Satoru, Proceedings, ... meeting of Japan Society of Fluid Mechanics, 2001, 469, 470,   2001 07 31 , http://ci.nii.ac.jp/naid/110003887090
    Summary:A large-eddy simulation (LES) based on a finite volume method was applied to a liquid turbulent flow with a rapid chemical reaction. The large eddy probability density function model was used as a subgrid-scale (SGS) model for a rapid reaction. The correlation coefficient in the scale similarity model between the variance of SGS concentration and that of test-filtered concentration was determined using the data of the DNS of liquid isotropic turbulence. To investigate the applicability of the LES to reacting liquid flows, both measurement and LES were performed in a liquid mixing layer wit h a rapid reaction. The prediction of the LES was in good agreement with the measurement. And the result also showed that the present LES can accurately estimate the concentration statistics in reacting liquid flows.
  • Large Eddy Simulation of Grid-Generated Turbulence with Chemical Reactions, MICHIOKA Takenobu, NAGATA Kouji, IDA Atsushi, KOMORI Satoru, Transactions of the Japan Society of Mechanical Engineers. B, 66, 651, 2815, 2822,   2000 11 25 , 10.1299/kikaib.66.651_2815, http://ci.nii.ac.jp/naid/110002392636
    Summary:A large eddy simulation (LES) based on a finite volume method was applied to a liquid mixing layer flow downstream of a turbulence-generating grid with chemical reactions. The large eddy probability density function (LEPDF) model and joint LEPDF model were used as a SGS model for a rapid reaction and for a moderately fast reaction, respectively. The results of the LES were compared with the measurements to examine the proposed subgrid-scale (SGS) models. Furthermore, the correlation coefficient in the scale similarity model between the variance of SGS concentration and that of test-filtered concentration was determined using the data of the direct numerical simulation (DNS) of liquid isotropic turbulence. The results show that the correlation coefficient for a liquid flow 5 is times bigger than that for a gas flow. When the appropriate correlation coefficent is given, the LES results are in good agreement with the measurements.
  • Large eddy simulation of grid-generated turbulence with chemical reactions, Takenobu Michioka, Kouji Nagata, Atsushi Ida, Satoru Komori, Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B, 66, 2815, 2822,   2000 11 01 , 10.1299/kikaib.66.651_2815, https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=77950088371&origin=inward
    Summary:A large eddy simulation (LES) based on a finite volume method was applied to a liquid mixing layer flow downstream of a turbulence-generating grid with chemical reactions. The large eddy probability density function (LEPDF) model and joint LEPDF model were used as a SGS model for a rapid reaction and for a moderately fast reaction, respectively. The results of the LES were compared with the measurements to examine the proposed subgrid-scale (SGS) models. Furthermore, the correlation coefficient in the scale similarity model between the variance of SGS concentration and that of test-filtered concentration was determined using the data of the direct numerical simulation (DNS) of liquid isotropic turbulence. The results show that the correlation coefficient for a liquid flow is 5 times bigger than that for a gas flow. When the appropriate correlation coefficent is given, the LES results are in good agreement with the measurements.
  • Large eddy simulation of turbulent liquid flows with chemical reactions, MICHIOKA Takenobu, Onishi Ryo, NAGATA Kouji, KOMORI Satoru, 年次大会講演論文集 : JSME annual meeting, 2000, 4, 237, 238,   2000 07 31 , http://ci.nii.ac.jp/naid/110002523311
    Summary:A large eddy simulation (LES) based on a finite volume method was applied to liquid mixing layer flow downstream of a turbulence-generating grid with a chemical reaction. The large eddy probability density function (LEPDF) model and joint LEPDF model were used as a SGS model for a rapid reaction and for a moderately fast reaction, respectively. The results of the LES were compared with the measurements to examine the proposed subgrid-scale (SGS) models. Furthermore, the correlation coefficient in the scale similarity model between the variance of SGS concentration and that of test-filtered concentration was determined using the data of the direct numerical simulation (DNS) of liquid isotropic turbulence. The results show that the correlation coefficient for a liquid flow is 5 times bigger than that for a gas flow. When the appropriate correlation coefficent is given, the LES results are in good agreement with the measurements.
  • A subgrid-scale model in les of turbulent reacting flows, Takenobu Michioka, Satoru Komori, Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B, 65, 839, 846,   1999 12 01 , 10.1299/kikaib.65.839, https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=71249094416&origin=inward
    Summary:A subgrid-scale model for the filtered reaction term is presented to develope the large eddy simulation (LES) of nonpremixed, turbulent reacting flows. The subgrid-scale model is based on the subgrid-scale probability density function (PDF) and subgrid-scale conditional expectation. The subgrid-scale PDF is assumed to follow the beta distribution and the subgrid-scale conditional expectation is given using the filtered data obtained from the direct numerical simulation of an air mixing-layer downstream of turbulence-generating grids with a second-order chemical reaction. Further, the subgrid scale model for the filtered reaction term is evaluated by comparing with the DNS. The results show that the subgrid-scale model can accurately estimate the filtered reaction term and it is applicable to the LES of turbulent reacting flows.
  • Modeling of a reaction term in Large eddy simulation, MICHIOKA Takenobu, IDA Atsushi, NAGATA Kouji, KOMORI Satoru, 年会一般講演, 18, 317, 318,   1999 07 29 , http://ci.nii.ac.jp/naid/10007478650

Research Grants & Projects

  • Ministry of Education, Culture, Sports, Science and Technology, Grants-in-Aid for Scientific Research(若手研究(B)), Effects of turbulent organized structures on gas dispersion in aurban area, Large-eddy simulations were conducted to investigate mechanismof pollutant gas removal form urban canyons under neutral, stable and unstable thermalstratification. The result shows that the gas removal from the canyon is strongly relatedto the size of the low-momentum fluid, defined as a region in the flow where instantaneousstreamwise velocity is lower than the local mean velocity. Irrespective of the thermalstratification, the ejection which transports low-momentum fluid upward has influenceon pollutant removal from the canyon.