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Dehbi, A.*; Cheng, X.*; Liao, Y.*; Okagaki, Yuria; Pellegrini, M.*
Proceedings of 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-19) (Internet), 15 Pages, 2022/03
Uenaga, Issei; Furukawa, Masaru*
Physics of Plasmas, 27(9), p.092501_1 - 092501_11, 2020/09
Times Cited Count：0 Percentile：0.00(Physics, Fluids & Plasmas)This work uses the Rutherford model for a cylindrical plasma to study the dynamics of magnetic islands under external magnetic perturbations, including both applied rotational magnetic fields and static error magnetic fields. The results show that, in an unstable tearing situation, magnetic islands are completely suppressed by modulating the frequency of the externally applied rotational magnetic field to maintain the phase of the combined external magnetic field to be opposite (or nearly opposite) that of the magnetic islands. The frequency is modulated by using a proportional controller in the simulation, where the frequency of the rotational field is determined by using the island rotation frequency "measured" in the simulation.
Kadowaki, Satoshi; Nogami, Masato*; Thwe Thwe, A.; Katsumi, Toshiyuki*; Yamazaki, Wataru*; Kobayashi, Hideaki*
Nihon Kikai Gakkai Rombunshu (Internet), 85(879), p.19-00274_1 - 19-00274_13, 2019/11
We dealt with three-dimensional cellular premixed flames generated by hydrodynamic and diffusive-thermal instabilities to elucidate the effects of unburned-gas temperature and heat loss by adopting the three-dimensional compressible Navier-Stokes equation. As the unburned-gas temperature became lower and the heat loss became larger, the growth rate decreased and the unstable range narrowed. With a decrease of unburned-gas temperature, the normalized growth rate increased and the normalized unstable range widened, which was because the temperature ratio of burned and unburned gases became larger. The obtained hexagonal cellular fronts were qualitatively consistent with the experimental results. As the heat loss became larger, the burning velocity of a cellular flame normalized by that of a planar flame increased. This was because diffusive-thermal effects became stronger owing to the increase of apparent Zeldovich number caused by the decrease of flame temperature.
Thwe Thwe, A.; Kadowaki, Satoshi; Hino, Ryutaro
Journal of Thermal Science and Technology (Internet), 13(2), p.18-00457_1 - 18-00457_12, 2018/12
Times Cited Count：0 Percentile：0.00(Thermodynamics)Two dimensional unsteady calculations of reactive flows were performed in large domain to investigate the unstable behaviors of cellular premixed flames at low Lewis numbers based on the diffusive-thermal (D-T) model and compressible Navier-Stokes (N-S) equations. The growth rates obtained by the compressible N-S equations were large and the unstable ranges were wide compared with those obtained by the D-T model equations. When the length of computational domain increased, the number of small cells separated from large cells of the cellular flame increased drastically. The stronger unstable behaviors and the larger average burning velocities were observed especially in the numerical results based on the compressible N-S equations. In addition, the fractal dimension obtained by the compressible N-S equations was larger than that by the D-T model equations. Moreover, we confirmed that the radiative heat loss promoted the instability of premixed flames at low Lewis numbers.
Peri
ez, R.*; Brovchenko, I.*; Duffa, C.*; Jung, K.-T.*; Kobayashi, Takuya; Lamego, F.*; Maderich, V.*; Min, B.-I.*; Nies, H.*; Osvath, I.*; et al.
Journal of Environmental Radioactivity, 150, p.247 - 269, 2015/12
Times Cited Count：37 Percentile：69.65(Environmental Sciences)A detailed intercomparison of marine dispersion models applied to the releases from Fukushima Dai-ichi Nuclear Power Plant has been carried out in the frame of MODARIA program, of the IAEA. Models have been compared in such a way that the reasons of the discrepancies between them can be assessed. The overall idea is to harmonize models, making them run with the same forcing in a step-by-step procedure, in such a way that the main agent in producing discrepancy between models can be found. It has been found that the main reason of discrepancies between models is due to the description of the hydrodynamics. However, once this has been suppressed, some variability between model outputs remains due to intrinsic differences between models. The numerical experiments have been carried out for a perfectly conservative radionuclide and for 
Cs. Model outputs for this radionuclide have also been compared with measurements in water and sediments.
n waves in tokamaksBierwage, A.; Shinohara, Koji
Physics of Plasmas, 21(11), p.112116_1 - 112116_21, 2014/11
Times Cited Count：25 Percentile：73.66(Physics, Fluids & Plasmas)Utsumi, Takayuki*; Yabe, Takashi*; Aoki, Takayuki*; Koga, J. K.; Yamagiwa, Mitsuru
JSME International Journal, Series B, 47(4), p.768 - 776, 2004/11
no abstracts in English
Furukawa, Masaru; Tokuda, Shinji
Journal of Plasma and Fusion Research SERIES, Vol.6, p.210 - 213, 2004/00
A model equation for ballooning modes in toroidally rotating tokamaks is derived. It is confirmed that the model equation is appropriate for analyzing the stabilization mechanism of the ballooning modes by comparing the numerical solutions of the model equation with those of the original ballooning equations.
Bottino, A.*; Angelino, P.*; Allfrey, S. J.*; Brunner, S.*; Hatzky, R.*; Idomura, Yasuhiro; Jolliet, S.*; Sauter, O.*; Tran, T. M.*; Villard, L.*
Theory of Fusion Plasmas, ISPP21, p.75 - 86, 2004/00
The global nonlinear electrostatic PIC code ORB5 solves the gyrokinetic Vlasov-Poisson system assuming adiabatic electrons in realistic tokamak magnetohydrodynamic (MHD) equilibria. The present version of ORB5 shows remarkable particle and energy conservation properties and can be used for physics studies in toroidal geometry. In particular, the optimized tracer loading method has been adapted to tokamak geometry and implemented in ORB5 together with a new adaptive gyro-average algorithm. Basic physical conservation properties (energy and particle number) are used as indicators of the quality of the numerical simulations. In this paper we present the first nonlinear results of electrostatic collisionless microinstabilities of realistic MHD shaped equilibria, provided by the MHD equilibrium code CHEASE, including the toroidicity induced geometrical coupling of the zonal ExB flow and the parallel velocity nonlinearlity.
Watanabe, Shoichi; Yamane, Yuichi; Miyoshi, Yoshinori
JAERI-Tech 2003-045, 73 Pages, 2003/03
JAERI-Tech-2003-045.pdf:4.96MB
Since exact information is not always acquired in the criticality accident of fuel-solution, parametric survey calculations are required for grasping behaviors of the thermal-hydraulics. On the other hand, the practical methods of the calculation which can reduce the computation time with allowable accuracy will be also required, since the conventional method takes a long calculation time. In order to fulfill the requirement, a three-dimensional nuclear-kinetics analysis code considering thermal-hydraulic based on the multi-region kinetic equations with one-group neutron energy was created by incorporating the thermal-hydraulics analysis code PHOENICS as a subroutine. The computation time of the code was shortened by separating time mesh intervals of the nuclear- and heat-calculations from that of the hydraulics calculation, and by regulating automatically the time mesh intervals in proportion to power change rate. A series of analysis were performed for the natural-cooling characteristic test using TRACY in which the power changed slowly for 5 hours after the transient power resulting from the reactivity insertion of a 0.5 dollar. It was found that the code system was able to calculate within the limit of practical time, and acquired the prospect of reproducing the experimental values considerably for the power and temperature change.
Tokuda, Shinji
Purazuma, Kaku Yugo Gakkai-Shi, 78(9), p.913 - 924, 2002/09
An introductory review is given on recent developments in the methods for stability analysis of a toroidally confined plasma. Emphasis is put on the perturbation analysis of a magnetohydrodynamic system that has the marginally stable state as a terminal point of continuous spectra. We address ourselves to the asymptotic matching method pertinent to such a problem. The Newcomb equation and inner-layer equations are essential ingredients in the methods and the numerical methods for solving them are discussed.
Utsumi, Takayuki*; Sasaki, Akira; Fujii, Sadao*
Keisan Kogaku Koenkai Rombunshu, 5, 4 Pages, 2000/05
no abstracts in English
Hasegawa, Yukihiro*; Nakamura, Yukiharu; Shirai, Hiroshi; Hamamatsu, Kiyotaka; Harada, Hiro; Kikuchi, Mitsuru;
Nihon Genshiryoku Gakkai-Shi, 41(1), p.48 - 56, 1999/00
Times Cited Count：2 Percentile：20.96(Nuclear Science & Technology)no abstracts in English
; Kunugi, Tomoaki*; ; Sasaki, Akira;
CIPUS Annual Report, 4 Pages, 1998/00
no abstracts in English
; Kunugi, Tomoaki
Comput. Model. Simul. Eng., 1(4), p.452 - 476, 1996/11
no abstracts in English
Rn concentration model using a hydrodynamic meteorological model,2; Three-demensional research-purpose modelChino, Masamichi; Yamazawa, Hiromi
Health Physics, 70(1), p.55 - 63, 1996/01
Times Cited Count：6 Percentile：49.73(Environmental Sciences)no abstracts in English
Rn concentration model using a hydrodynamic meteorological model,1; One dimensional practical modelChino, Masamichi; Yamazawa, Hiromi; Iida, Takao*
Health Physics, 70(1), p.47 - 54, 1996/01
Times Cited Count：3 Percentile：32.42(Environmental Sciences)no abstracts in English
Kunugi, Tomoaki; ;
Dai-32-Kai Nihon Dennetsu Shimpojiumu Koen Rombunshu, 0, p.565 - 566, 1995/05
no abstracts in English
Akiba, Masato; R.D.Watson*
Atomic and Plasma-Material Interaction Processes in Controlled Thermonuclear Fusion, p.455 - 480, 1993/00
no abstracts in English
Maeda, Mitsuru; Fujine, Sachio; Uchiyama, Gunzo; ; ; ; ;
Solvent Extraction in the Process Industries, Vol. 3, p.1517 - 1523, 1993/00
no abstracts in English
