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Journal Articles

A Comparative CFD exercise on bubble hydrodynamics using Euler-Euler and interface tracking approaches

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

Journal Articles

Three-dimensional cellular premixed flames generated by hydrodynamic and diffusive-thermal instabilities (Effects of unburned-gas temperature and heat loss)

Kadowaki, Satoshi; Nogami, Masato*; Thwe, T. 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.

Journal Articles

Numerical investigation on unstable behaviors of cellular premixed flames at low Lewis numbers based on the diffusive-thermal model and compressible Navier-Stokes equations

Thwe, T. 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:0.01(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.

Journal Articles

A New comparison of marine dispersion model performances for Fukushima Dai-ichi releases in the frame of IAEA MODARIA program

Peri$'a$$~n$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:23 Percentile:68.57(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 $$^{137}$$Cs. Model outputs for this radionuclide have also been compared with measurements in water and sediments.

Journal Articles

Orbit-based analysis of resonant excitations of Alfv$'e$n waves in tokamaks

Bierwage, A.; Shinohara, Koji

Physics of Plasmas, 21(11), p.112116_1 - 112116_21, 2014/11

 Times Cited Count:19 Percentile:72.88(Physics, Fluids & Plasmas)

Journal Articles

Solutions of hyperbolic equations with the CIP-BS method

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

Journal Articles

A Model equation for ballooning modes in toroidally rotating tokamaks

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.

Journal Articles

Recent advances in nonlinear gyrokinetic PIC simulations in tokamak geometry

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.

JAEA Reports

Development of a kinetics analysis code for fuel solution combined with thermal-hydraulics analysis code PHOENICS and analysis of natural-cooling characteristic test of TRACY (Contract research)

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.

Journal Articles

Singular point analysis

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.

Journal Articles

Simulation of solid irradiated with high power ultrashort pulse laser; The behavior of laser beam propagating in the plasma

Utsumi, Takayuki*; Sasaki, Akira; Fujii, Sadao*

Keisan Kogaku Koenkai Rombunshu, 5, 4 Pages, 2000/05

no abstracts in English

Journal Articles

Development and performance of high speed processing system of magnetohydrodynamic equilibria for discharge analyses on the JT-60 tokamak

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:21.95(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Numerical simulation of solid matter melting by CIP method

*; Kunugi, Tomoaki*; *; Sasaki, Akira; *

CIPUS Annual Report, 4 Pages, 1998/00

no abstracts in English

Journal Articles

Solving wave equations with the differential algebraic-cubic interpolated propagation scheme

*; Kunugi, Tomoaki

Comput. Model. Simul. Eng., 1(4), p.452 - 476, 1996/11

no abstracts in English

Journal Articles

Development of an atmospheric $$^{222}$$Rn concentration model using a hydrodynamic meteorological model,1; One dimensional practical model

Chino, Masamichi; Yamazawa, Hiromi; Iida, Takao*

Health Physics, 70(1), p.47 - 54, 1996/01

 Times Cited Count:3 Percentile:33.71(Environmental Sciences)

no abstracts in English

Journal Articles

Development of an atmospheric $$^{222}$$Rn concentration model using a hydrodynamic meteorological model,2; Three-demensional research-purpose model

Chino, Masamichi; Yamazawa, Hiromi

Health Physics, 70(1), p.55 - 63, 1996/01

 Times Cited Count:6 Percentile:51.24(Environmental Sciences)

no abstracts in English

Journal Articles

Numerical simulation of thermo-fluid flow of non-equilibrium plasma impinging jet

Kunugi, Tomoaki; *; *

Dai-32-Kai Nihon Dennetsu Shimpojiumu Koen Rombunshu, 0, p.565 - 566, 1995/05

no abstracts in English

Journal Articles

Thermo-hydrodynamic coupling with coolants

Akiba, Masato; R.D.Watson*

Atomic and Plasma-Material Interaction Processes in Controlled Thermonuclear Fusion, p.455 - 480, 1993/00

no abstracts in English

Journal Articles

Simulation code of extraction contactor for analyzing transient behavior

Maeda, Mitsuru; Fujine, Sachio; Uchiyama, Gunzo; *; *; ; *; *

Solvent Extraction in the Process Industries, Vol. 3, p.1517 - 1523, 1993/00

no abstracts in English

Journal Articles

Simulation code SAFE for analyzing transient solvent extraction behavior

Maeda, Mitsuru; Fujine, Sachio; *; *

Transactions of the American Nuclear Society, 66, p.78 - 80, 1992/11

no abstracts in English

69 (Records 1-20 displayed on this page)