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Onodera, Naoyuki; Idomura, Yasuhiro; Hasegawa, Yuta; Asahi, Yuichi; Inagaki, Atsushi*; Shimose, Kenichi*; Hirano, Kohin*
Keisan Kogaku Koenkai Rombunshu (CD-ROM), 28, 4 Pages, 2023/05
We have developed a multi-scale wind simulation code named CityLBM that can resolve entire cities to detailed streets. CityLBM enables a real time ensemble simulation for several km square area by applying the locally mesh-refined lattice Boltzmann method on GPU supercomputers. On the other hand, real-world wind simulations contain complex boundary conditions that cannot be modeled, so data assimilation techniques are needed to reflect observed data in the simulation. This study proposes an optimization method for ground surface temperature bias based on an ensemble Kalman filter to reproduce wind conditions within urban city blocks. As a verification of CityLBM, an Observing System Simulation Experiment (OSSE) is conducted for the central Tokyo area to estimate boundary conditions from observed near-surface temperature values.
Watanabe, Tsutomu*; Takagi, Marie*; Shimoyama, Ko*; Kawashima, Masayuki*; Onodera, Naoyuki; Inagaki, Atsushi*
Boundary-Layer Meteorology, 181(1), p.39 - 71, 2021/10
Times Cited Count：6 Percentile：47.35(Meteorology & Atmospheric Sciences)A double-distribution-function lattice Boltzmann model for large-eddy simulations of a passive scalar field is described within and above a plant canopy. For a top-down scalar, for which the plant canopy serves as a distributed sink, the flux of the scalar near the canopy top are predominantly determined by sweep motions originating far above the canopy. By contrast, scalar ejection events are induced by coherent eddies generated near the canopy top. In this paper, the generation of such eddies is triggered by the downward approach of massive sweep motions to existing wide regions of weak ejective motions from inside to above the canopy.
Takeda, Tetsuaki*; Inagaki, Yoshiyuki; Aihara, Jun; Aoki, Takeshi; Fujiwara, Yusuke; Fukaya, Yuji; Goto, Minoru; Ho, H. Q.; Iigaki, Kazuhiko; Imai, Yoshiyuki; et al.
High Temperature Gas-Cooled Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.5, 464 Pages, 2021/02
As a general overview of the research and development of a High Temperature Gas-cooled Reactor (HTGR) in JAEA, this book describes the achievements by the High Temperature Engineering Test Reactor (HTTR) on the designs, key component technologies such as fuel, reactor internals, high temperature components, etc., and operational experience such as rise-to-power tests, high temperature operation at 950
C, safety demonstration tests, etc. In addition, based on the knowledge of the HTTR, the development of designs and component technologies such as high performance fuel, helium gas turbine and hydrogen production by IS process for commercial HTGRs are described. These results are very useful for the future development of HTGRs. This book is published as one of a series of technical books on fossil fuel and nuclear energy systems by the Power Energy Systems Division of the Japan Society of Mechanical Engineers.
Yokouchi, Hiroshi*; Inagaki, Atsushi*; Kanda, Manabu*; Onodera, Naoyuki
Doboku Gakkai Rombunshu, B1 (Suikogaku) (Internet), 76(2), p.I_253 - I_258, 2020/00
Hight-resolution pollutant model embedded into Lattice Boltzmann method (LBM) is constructed. We focuses on Particle pollutants. Flow field is calculated using D3Q27 model of LBM and particle is calculated by Lagrangian method. Using this model, we discuss the change in concentration distribution when there is a huge building (GARUDA) in Jakarta as a application. As a result, we can find the relation of differences in particle density and differences in flow velocity due to GARUDA. When the velocity in the case w/o GARUDA is faster than the other, particle velocity in the case w/o GARUDA is reduced. And also, we can find the velocity near the solid boundary is underestimated and the particle density is higher than theoretical value. However, this model is valid far away from the solid boundary.
Inagaki, Atsushi*; Wangsaputra, Y.*; Kanda, Manabu*; Y
cel, M.*; Onodera, Naoyuki; Aoki, Takayuki*
SOLA (Scientific Online Letters on the Atmosphere) (Internet), 16, p.120 - 124, 2020/00
Times Cited Count：1 Percentile：4.56(Meteorology & Atmospheric Sciences)The similarity of the turbulence intensity profile with the inner-layer and the outer-layer scalings were examined for an urban boundary layer using numerical simulations. The simulations consider a developing neutral boundary layer over realistic building geometry. The computational domain covers an 19.2 km by 4.8 km and extends up to a height of 1 km with 2-m grids. Several turbulence intensity profiles are defined locally in the computational domain. The inner- and outer-layer scalings work well reducing the scatter of the turbulence intensity within the inner- and outer-layers, respectively, regardless of the surface geometry. Although the main scatters among the scaled profiles are attributed to the mismatch of the parts of the layer and the scaling parameters, their behaviors can also be explained by introducing a non-dimensional parameter which consists of the ratio of length or velocity.
, and COSYoshida, Go*; Ninomiya, Kazuhiko*; Inagaki, Makoto*; Higemoto, Wataru; Strasser, P.*; Kawamura, Naritoshi*; Shimomura, Koichiro*; Miyake, Yasuhiro*; Miura, Taichi*; Kubo, Kenya*; et al.
Journal of Radioanalytical and Nuclear Chemistry, 320, p.283 - 289, 2019/05
Times Cited Count：4 Percentile：41.24(Chemistry, Analytical)The role of valence electrons for the muon capture process by molecules is experimentally investigated with the aid of cascade calculations. Low-momentum muons are introduced to gas targets below atmospheric pressure. The initial states of captured muons are determined from the measured muonic X-ray structure of the Lyman and Balmer series. We propose that the lone pair electrons in the carbon atom of CO significantly contribute to the capture of a muon with large angular momenta.
Inagaki, Atsushi*; Kanda, Manabu*; Ahmad, N. H.*; Yagi, Ayako*; Onodera, Naoyuki; Aoki, Takayuki*
Boundary-Layer Meteorology, 164(2), p.161 - 181, 2017/08
Times Cited Count：30 Percentile：75.23(Meteorology & Atmospheric Sciences)The applicability of outer-layer scaling is examined by numerical simulation of a developing neutral boundary layer over a realistic building geometry of Tokyo. Large-eddy simulations are carried out over a large computational domain 19.2 km 
4.8 km 1 km, with a fine grid spacing (2 m) using the lattice-Boltzmann method with massively parallel graphics processing units. Results from simulations show that outer-layer features are maintained for turbulence statistics in the upper part of the boundary layer, as well as the width of predominant streaky structures throughout the entire boundary layer. This is caused by the existence of very large streaky structures extending throughout the entire boundary layer, which follow outer-layer scaling with a self-preserving development. We assume the top-down mechanism in the physical interpretation of results.
Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Makino, Hitoshi; Wakasugi, Keiichiro; Mitsui, Seiichiro; Kitamura, Akira; Yoshikawa, Hideki; Oda, Chie; Ishidera, Takamitsu; et al.
JAEA-Research 2014-030, 457 Pages, 2015/03
JAEA-Research-2014-030.pdf:199.23MB
JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and post-closure performance assessment in preliminary investigation stage. With regard to (1) study on rock suitability in terms of hydrology, based on some examples of developing method of hydro-geological structure model, acquired knowledge are arranged using the tree diagram, and model uncertainty and its influence on the evaluation items were discussed. With regard to (2) study on scenario development, the developed approach for "defining conditions" has been reevaluated and improved from practical viewpoints. In addition, the uncertainty evaluation for the effect of use of cementitious material, as well as glass dissolution model, was conducted with analytical evaluation. With regard to (3) study on setting radionuclide migration parameters, based on survey of precedent procedures, multiple-approach for distribution coefficient of rocks was established, and the adequacy of the approach was confirmed though its application to sedimentary rock and granitic rock. Besides, an approach for solubility setting was developed including the procedure of selection of solubility limiting solid phase. The adequacy of the approach was confirmed though its application to key radionuclides.
Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Hayano, Akira; Makino, Hitoshi; Wakasugi, Keiichiro; Mitsui, Seiichiro; Oda, Chie; Kitamura, Akira; Osawa, Hideaki; et al.
JAEA-Research 2013-037, 455 Pages, 2013/12
JAEA-Research-2013-037.pdf:42.0MB
Following FY2011, JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and performance assessment in preliminary investigation stage. With regard to (1) study on rock suitability in terms of hydrology, the tree diagram of methodology of groundwater travel time has been extended for crystalline rock, in addition, tree diagram for sedimentary rock newly has been organized. With regard to (2) study on scenario development, the existing approach has been improved in terms of a practical task, and applied and tested for near field focusing on the buffer. In addition, the uncertainty of some important processes and its impact on safety functions are discussed though analysis. With regard to (3) study on setting radionuclide migration parameters, the approaches for parameter setting have been developed for sorption for rocks and solubility, and applied and tested through parameter setting exercises for key radionuclides.
Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Makino, Hitoshi; Hayano, Akira; Mitsui, Seiichiro; Taniguchi, Naoki; Oda, Chie; Kitamura, Akira; Osawa, Hideaki; et al.
JAEA-Research 2012-032, 298 Pages, 2012/09
JAEA-Research-2012-032.pdf:33.68MB
JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and performance assessment in preliminary investigation phase. The topics and the conducted research are follows; (1) Study on selection of host rock: in terms of hydraulic properties, items for assessing rock property, and assessment methodology of groundwater travel time has been organized with interaction from site investigation. (2) Study on development of scenario: the existing approach has been embodied, in addition, the phenomenological understanding regarding dissolution of and nuclide release from vitrified waste, corrosion of the overpack, long-term performance of the buffer are summarized. (3) Study on setting nuclide migration parameters: the approach for parameter setting has been improved for sorption and diffusion coefficient of buffer/rock, and applied and tested for parameter setting of key radionuclides. (4) Study on ensuring quality of knowledge: framework for ensuring quality of knowledge has been studied and examined aimed at the likely disposal facility condition.
Inagaki, Yaohiro*; Sakatani, Keiichi*; Yamamura, Yuki*; Mitsui, Seiichiro; Noshita, Kenji*; Miura, Yoshiyuki*; Kanehira, Norio*; Ochi, Eiji*; Mukunoki, Atsushi*; Chiba, Tamotsu*
Dai-7-Kai Saishori, Risaikuru Bukai Semina Tekisuto, p.136 - 137, 2011/01
Conventional static test methods are not appropriate to evaluate glass dissolution behavior at an arbitrarily-fixed condition due to compositional change of the solution with glass dissolution. In this study, we applied a newly-devised micro-channel flow-through test method to measurement of the initial dissolution rates of Japanese simulated waste glasses, JAEA-P0798 and JNFL-KMOC, at arbitrarily-fixed conditions and we evaluated temperature and pH dependence of glass dissolution. The results showed that the initial dissolution rate increased with temperature and had "V-shaped" pH dependence at each temperature.
Iwatsuki, Teruki; Sato, Haruo; Tanai, Kenji; Inagaki, Manabu; Sawada, Atsushi; Niinuma, Hiroaki; Ishii, Eiichi; Maekawa, Keisuke; Tomura, Goji; Sanada, Hiroyuki; et al.
JAEA-Research 2009-002, 156 Pages, 2009/05
JAEA-Research-2009-002.pdf:12.86MB
The research and development plan for geological investigation, engineering technology and safety assessment during the drilling of a shaft down to intermediate depth are summarized according to the Midterm Plan till 2009 Fiscal year of JAEA. This report describes subject, current status and programme in the "Phase 2: Construction phase" (investigations during construction of the underground facilities). Furthermore regarding R&D plan in next Midterm Plan of JAEA, preliminary ideas are summarized.
Maekawa, Keisuke; Sawada, Atsushi; Inagaki, Manabu; Oi, Takao
no journal, ,
no abstracts in English
Hayano, Akira; Sawada, Atsushi; Goto, Junichi*; Ishii, Eiichi*; Moriya, Toshifumi*; Inagaki, Manabu*; Kubota, Shigeru*; Ebashi, Takeshi*
no journal, ,
Detailed Investigation Areas have to be selected with focusing on suitability of the host rock in the siting process for high-level radioactive waste disposal in Japan. The suitability of the host rock is evaluated in terms of the preferable disposal condition such as thermal, hydraulic, mechanical and geochemical condition, and the feasibility of the geological disposal project relevant to volumetric capacity of host rock and economics, based on the site model. However, due to a limited number of surveys at relatively early stage of the investigation, the lack of understanding of geological environment at the site causes an uncertainty of the site model. It is essential to clarify an association the important factors relevant to safety assessment (SA) and a repository design (Design) with the information obtained by the site investigation through the site model. In this study, the methodology not only for defining evaluation factors relevant to SA in term of hydrogeology, but also for visualizing the methods to evaluate the factors through the site model is organized into a tree diagram. A method to evaluate groundwater travel time which is one of evaluation factors in granitic rock is organized into a first version of the tree diagram.
Sawada, Atsushi; Hayano, Akira; Goto, Junichi*; Inagaki, Manabu*
no journal, ,
no abstracts in English
Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Inagaki, Manabu*; Kurosawa, Susumu*; Goto, Junichi*; Shibutani, Sanae*
no journal, ,
no abstracts in English
Sawada, Atsushi; Hayano, Akira; Goto, Junichi*; Inagaki, Manabu*
no journal, ,
no abstracts in English
Inagaki, Atsushi*; Onodera, Naoyuki; Kanda, Manabu*; Aoki, Takayuki*
no journal, ,
Since urban atmospheric environment is strongly controlled by multi-scale flow dynamics, simulation of the urban atmospheric boundary layer requires fine grid spacing and huge computational domain. We accomplished to simulate an urban atmospheric boundary layer using a Large Eddy Simulation model running on TSUBAME super computing system. Flow characteristics within and above a building canopy were successfully examined.
Soma, Yasutaka; Komatsu, Atsushi; Ueno, Fumiyoshi; Inagaki, Hiromitsu*
no journal, ,
Corrosion condition within crevice of stainless steel is important to understand dissolution mechanisms of crack tip of stress corrosion cracking (SCC) in high-temperature water. We have reported that electrical conductivity of solution within crevice of stainless steel (
crev) exposed to high temperature and high purity water containing sufficient dissolved oxygen (DO) become more than 2 orders of magnitude higher than that for bulk pure water. In this study effect of conductivity and DO concentration of bulk water on crev of Type-316L stainless steel have been studied in 288C water. Following conclusion have been obtained: (1) crev increased with increasing DO concentration from 3 ppb to approximately 300 ppb. Above 300 ppb, crev did not simply increased with DO concentraion. (2) maximum crev was not affected by bulk water conductivity suggested that crev would be determined by chemical equilibrium reaction. (3) crev-time curves were not affected by crevice depth. It was assumed that anion required to increase crev generated within the crevice.
Onodera, Naoyuki; Hasegawa, Yuta; Idomura, Yasuhiro; Asahi, Yuichi; Kawamura, Takuma; Ina, Takuya; Shimomura, Kazuya; Inagaki, Atsushi*; Suzuki, Shinichi*; Hirano, Kohin*; et al.
no journal, ,
Wind prediction based on digital twin is a promising technology that can contribute to the construction of new social infrastructures, including applications to smart city design and operation. In this poster presentation, we will introduce wind simulations based on data assimilation with observations and mesoscale meteorological data for the realization of a digital twin of wind conditions in urban areas.
