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Kondo, Hiroo*; Kanemura, Takuji*; Park, C. H.*; Oyaizu, Makoto*; Hirakawa, Yasushi; Furukawa, Tomohiro
Fusion Engineering and Design, 146(Part A), p.285 - 288, 2019/09
Times Cited Count：1 Percentile：8.25(Nuclear Science & Technology)Herein, the wall shear stress in a double contraction nozzle has been evaluated experimentally to produce a liquid lithium (Li) target as a beam target for intense fusion neutron sources such as the International Fusion Materials Irradiation Facility (IFMIF), the Advanced Fusion Neutron Source (A-FNS), and the DEMO Oriented Neutron Source (DONES). The boundary layer thickness and wall shear stress are essential physical parameters to understand erosion-corrosion by the high-speed liquid Li flow in the nozzle, which is the key component in producing a stable Li target. Therefore, these parameters were experimentally evaluated using an acrylic mock-up of the target assembly. The velocity distribution in the nozzle was measured by a laser-doppler velocimeter and the momentum thickness along the nozzle wall was calculated using an empirical prediction method. The resulting momentum thickness was used to estimate the variation of the wall shear stress along the nozzle wall. Consequently, the wall shear stress was at the maximum in the second convergent section in front of the nozzle exit.
Furuno, Akiko; Terada, Hiroaki; Chino, Masamichi; Yamazawa, Hiromi*
Atmospheric Environment, 38(40), p.6989 - 6998, 2004/12
Times Cited Count：21 Percentile：41.62(Environmental Sciences)We have been developing the computer-based emergency response system WSPEEDI which predicts long-range atmospheric dispersion of radionuclides discharged into the atmosphere due to a nuclear accident. The first version of WSPEEDI has a shortage that the spatial and temporal variation of the atmospheric boundary layer was very simply parameterized. Therefore we have developed the new version accomplished with the atmospheric dynamic model, in which the turbulent diffusivity in the mixing layer is calculated with a turbulence closure model. This paper describes the results of performance evaluation of the new version of WSPEEDI by comparing the simulation results with the European Tracer Experiment data. As a result of the verification, it was shown that the increase in the horizontal resolution largely improved the accuracy of the model prediction. The use of the turbulence closure model instead of the simple parameterization largely contributed to improve reproducibility of horizontal distribution of plumes.
Terada, Hiroaki; Furuno, Akiko; Chino, Masamichi
Journal of Nuclear Science and Technology, 41(5), p.632 - 640, 2004/05
Times Cited Count：23 Percentile：79.14(Nuclear Science & Technology)The new version of WSPEEDI (Worldwide version of System for Prediction of Environmental Emergency Dose Information) is developed by introducing the combination of models, the atmospheric dynamic model MM5 and the Lagrangian particle dispersion model GEARN-new to improve the prediction capability. One of the improvements by the new system is that Environmental contaminations in multi domains are predicted simultaneously, and the other is that more precise physical processes are considered by using predicted meteorological conditions with high resolution in time and space. The performance of the system is evaluated for the test calculations of hypothetical nuclear accident in the East Asia region and the Chernobyl accident. The results of test calculation in East Asia seem to be reasonable and the calculated surface air concentrations of 
Cs from Chernobyl show good agreement with measurements.
Tokuda, Shinji
Theory of Fusion Plasmas, p.87 - 102, 2002/00
We report on recent development of solution methods of the Newcomb equation and boundary layer equations, which play important roles in MHD stability analysis of a tokamak. Especially, the two-dimensional Newcomb equation is applied to external modes and the method is desctribed for computing the stability matrix of the external modes.
Ishizawa, Akihiro; Tokuda, Shinji
Physics of Plasmas, 7(3), p.875 - 882, 2000/03
Times Cited Count：15 Percentile：42.91(Physics, Fluids & Plasmas)no abstracts in English
Ito, Kazuhiro*; Tsuji, Yoshiyuki*; Nakamura, Hideo; Kukita, Yutaka*
Fusion Technology, 36(1), p.69 - 84, 1999/07
no abstracts in English
Tokuda, Shinji;
JAERI-Research 96-044, 102 Pages, 1996/08
JAERI-Research-96-044.pdf:2.3MB
no abstracts in English
; ;
Taiki Osen Gakkai-Shi, 20(3), p.158 - 167, 1985/00
no abstracts in English
; ;
JAERI-M 83-233, 60 Pages, 1984/01
no abstracts in English
Nakayama, Hiromasa; Takemi, Tetsuya*
no journal, ,
In using Large-Eddy Simulation (LES) in study fields of computational fluid engineering, boundary layer meteorology, and atmospheric dispersion, one of difficult problems is a treatment of turbulent inflow boundary. The variability of atmospheric flow is induced by meteorological disturbances, terrains, and surface roughness elements. Therefore, wind velocities are also always changed. In conducting LESs, time-dependent turbulent inflow data have to be imposed at the inlet boundary depending on the atmospheric conditions. In this study, from a practical application perspective, we propose a generation method for thermally-stratified boundary layer flows by a short fetch and discuss the effectiveness of the approach in comparison to the existing wind tunnel experimental data.
