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Soma, Shu; Ishigaki, Masahiro*; Abe, Satoshi; Shibamoto, Yasuteru
Nuclear Engineering and Technology, 10 Pages, 2024/00
Onodera, Naoyuki; Idomura, Yasuhiro; Hasegawa, Yuta; Shimokawabe, Takashi*; Aoki, Takayuki*
Keisan Kogaku Koenkai Rombunshu (CD-ROM), 27, 4 Pages, 2022/06
We have developed a wind simulation code named CityLBM to realize wind digital twins. Mesoscale wind conditions are given as boundary conditions in CityLBM by using a nudging data assimilation method. It is found that conventional approaches with constant nudging coefficients fail to reproduce turbulent intensity in long time simulations, where atmospheric stability conditions change significantly. We propose a dynamic parameter optimization method for the nudging coefficient based on a particle filter. CityLBM was validated against plume dispersion experiments in the complex urban environment of Oklahoma City. The nudging coefficient was updated to reduce the error of the turbulent intensity between the simulation and the observation, and the atmospheric boundary layer was reproduced throughout the day.
Asakura, Nobuyuki; Takenaga, Hidenobu; Sakurai, Shinji; Porter, G. D.*; Rognlien, T. D.*; Rensink, M. E.*; Shimizu, Katsuhiro; Higashijima, Satoru; Kubo, Hirotaka
Nuclear Fusion, 44(4), p.503 - 512, 2004/04
Times Cited Count：73 Percentile：89.68(Physics, Fluids & Plasmas)The measurements of the SOL flow and plasma profiles both at the high-field-side (HFS) and low-field-side (LFS), for the first time, found out the SOL flow pattern and its driving mechanism. "Flow reversal" was found near the HFS and LFS separatrix of the main plasma for the ion ▽B drift direction towards the divertor. Radial profiles of the SOL flow were similar to those calculated numerically using the UEDGE code with the plasma drifts included although Mach numbers in measurements were faster than those obtained numerically. Particle fluxes towards the HFS and LFS divertors produced by the parallel SOL flow and Er
B drift flow were evaluated. The particle flux for the case of intense gas puff and divertor pump (puff and pump) was investigated, and it was found that both flow velocity and collisionality were enhanced, in particular, at HFS SOL. Drift flux in the private flux region was also evaluated, and important physics issues for the divertor design and operation, such as in-out asymmetries of the heat and particle fluxes, and control of impurity ions were investigated.
Ida, Mizuho*; Nakamura, Hideo; Nakamura, Hiroo; Takeuchi, Hiroshi
Fusion Engineering and Design, 70(2), p.95 - 106, 2004/02
Times Cited Count：18 Percentile：74.02(Nuclear Science & Technology)no abstracts in English
Asakura, Nobuyuki; Sakurai, Shinji; Itami, Kiyoshi; Naito, Osamu; Takenaga, Hidenobu; Higashijima, Satoru; Koide, Yoshihiko; Sakamoto, Yoshiteru; Kubo, Hirotaka; Porter, G. D.*
Journal of Nuclear Materials, 313-316, p.820 - 827, 2003/03
Times Cited Count：36 Percentile：89.58(Materials Science, Multidisciplinary)no abstracts in English
Asakura, Nobuyuki; Shimizu, Katsuhiro; Nakano, Tomohide; Higashijima, Satoru; Kubo, Hirotaka; Takenaga, Hidenobu
Proceedings of 30th EPS Conference on Controlled Fusion and Plasma Physics (CD-ROM), 4 Pages, 2003/00
The measurements of the parallel SOL flow (Mach number, M) and electric field (Er) both at the high-field-side (HFS) and low-field-side (LFS) have been accomplished using Mach probes in JT-60U. Particle fluxes towards the HFS and LFS divertors produced by the parallel SOL flow (niMCs) and ErxB drift flow (niEr/B) were evaluated. For the case of intense gas puffing from the plasma top (puff and pump), Zeff was reduced largely to 1.3, comparing to 1.42 for the divertor gas puff. It was found that both M and ni in niMCs were enhanced, in particular, at HFS. On the other hand, niEr/B for the two cases were comparable since ni increased and Er decreased for the puff and pump. Friction force and thermal force on impurity ions were estimated from the measured M, ne, Te and Ti, and ratios of Ffric/Fi-therm at HFS increased to 3-4 compared to 1.5-1.8 for the divertor gas puff. This result was consistent with a conventional model of reduction in Zeff. Two-dimensional transport of the carbon impurity at the HFS and LFS divertors was discussed using IMPMC (Impurity Monte-Carlo) code.
Asakura, Nobuyuki; Takenaga, Hidenobu; Sakurai, Shinji; Sakasai, Akira; Tamai, Hiroshi; Shimizu, Katsuhiro; Porter, G. D.*
Plasma Physics and Controlled Fusion, 44(10), p.2101 - 2119, 2002/10
Times Cited Count：21 Percentile：54.51(Physics, Fluids & Plasmas)no abstracts in English
Asakura, Nobuyuki; Sakurai, Shinji; Naito, Osamu; Itami, Kiyoshi; Miura, Yukitoshi; Higashijima, Satoru; Koide, Yoshihiko; Sakamoto, Yoshiteru
Plasma Physics and Controlled Fusion, 44(5A), p.A313 - A321, 2002/05
Times Cited Count：22 Percentile：57.23(Physics, Fluids & Plasmas)no abstracts in English
Asakura, Nobuyuki; Loarte, A.*; Porter, G.*; Philipps, V.*; Lipschultz, B.*; Kallenbach, A.*; Matthews, G.*; Federici, G.*; Kukushkin, A.*; Mahdavi, A.*; et al.
IAEA-CN-94/CT/P-01, 5 Pages, 2002/00
Three important physics issues for the ITER divertor design and operation are summarized based on the experimental and numerical work from multi-machine database (JET, JT-60U, ASDEX Upgrade, DIII-D, Alcator C-Mod and TEXTOR). (i) The energy load associated with Type-I ELMs is of great concern for the lifetime of the ITER divertor target. In order to understand the physics base of the scaling models, the ELM heat and particle transport to the divertor is investigated. Convective transport during ELMs plays an important role in heat transport to the divertor. (ii) Determination of the SOL flow pattern and the driving mechanism has progressed experimentally and numerically. Influences of the drift effects on the SOL and divertor plasma transport were discussed. (iii) Characteristics of chemical yield at two different deposited carbon surfaces, i.e. erosion- and redeposition-dominated areas, have been studied. Progress of understanding the chemical erosion is reviewed.
Hidaka, Akihide; Shibazaki, Hiroaki*; Yoshino, T.*; Sugimoto, Jun
Journal of Aerosol Science, 31(9), p.1045 - 1059, 2000/09
Times Cited Count：1 Percentile：18.22(Engineering, Chemical)no abstracts in English
Hidaka, Akihide; Shibazaki, Hiroaki*; Maruyama, Yu; Yoshino, T.*; Sugimoto, Jun
NEA/CSNI/R(98)4, 14 Pages, 2000/02
no abstracts in English
PNC TN9410 94-182, 29 Pages, 1994/06
A three-dimensional temperature fluctuation analysis was carried out using a general-purpose multi-dimensional thermohydraulics direct numerical simulation code DINUS-3 for parallel impinging jet experiments in sodium and water simulating thermal striping phenomena. The code utilized a third-order upwind scheme and an adaptive control system based on the Fuzzy theory to control time step sizes. The calculated results in both the cases showed evident differences mainly attributed to fluid properties such as heat conductivity, molecular viscosity, etc.. From the analysis, the following conclusions were obtained. (1)The amount of the temperature fluctuation damping by fluid mixing in sodium flow shows approximately two times larger than in water flow. While the damping amounts due to the laminar sub-layer in sodium flow is approximately 1/3 of that in water flow, (2)The variance of the probabilily density function for the calculated sodium temperature fluctuations is two times of the calculated water temperature fluctuations, and (3)The histogram of the normalized amplitude for calculated water temperature fluctuations can be fitted by a Layleigh distribution. By contrast, in the sodium case, the profile is very much like a exponential distribution. The results obtained in this work are very encouraging; the DINUS-3 code is one of the efficient measures to evaluate thermal striping phenomena in sodium, a low Prandtl number fluid, when one wishes to perform thermal striping evaluation in Liquid Metal Fast Breeder Reactors.
Yamazawa, Hiromi
Tenki, 40(2), p.99 - 107, 1993/02
no abstracts in English
Nihon Kikai Gakkai Rombunshu, B, 53(496), p.3742 - 3747, 1987/00
no abstracts in English
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Ranryu No Suchi Shimyureshon, p.63 - 71, 1987/00
no abstracts in English
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Nuclear Fusion, 18(6), p.849 - 857, 1978/06
Times Cited Count：19no abstracts in English
Ito, Kei; Ezure, Toshiki; Kunugi, Tomoaki*; Ohshima, Hiroyuki
no journal, ,
no abstracts in English
