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Sasa, Narimasa
Journal of the Physical Society of Japan, 91(5), p.054001_1 - 054001_8, 2022/05
Times Cited Count：0 Percentile：0.00(Physics, Multidisciplinary)Mochimaru, Takanori*; Koizumi, Mitsuo; Takahashi, Tone; Hironaka, Kota; Kimura, Yoshiki; Sato, Yuki; Terasaka, Yuta; Yamanishi, Hirokuni*; Wakabayashi, Genichiro*
Dai-42-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2021/11
no abstracts in English
Saito, Kimiaki
Isotope News, (773), p.3 - 6, 2021/02
no abstracts in English
Saito, Kimiaki
Genshiryoku No Ima To Ashita, p.148 - 151, 2019/03
no abstracts in English
Matsuoka, Seikichi; Idomura, Yasuhiro; Satake, Shinsuke*
Physics of Plasmas, 25(2), p.022510_1 - 022510_10, 2018/02
Times Cited Count：17 Percentile：73.90(Physics, Fluids & Plasmas)Global full-f gyrokinetic simulations, in which the gyrokinetic equation is solved based on the first principle without the scale separation with respect to the plasma distribution function, is attracting much attention in the plasma transport simulation studies. In this work, in order to apply a global full-f gyrokinetic simulation code GT5D to stellarator plasmas with complicated three-dimensional magnetic field configurations, we extend finite difference scheme of GT5D and develop a new interface code which incorporates the three-dimensional magnetic equilibria provided by a standard equilibrium code, VMEC. A series of benchmark calculations are carried out for the numerical verification of GT5D. It is successfully demonstrated that GT5D well reproduces results of a theoretical analysis and another global neoclassical transport code.
Matsuoka, Seikichi; Idomura, Yasuhiro; Satake, Shinsuke*
Physics of Plasmas, 24(10), p.102522_1 - 102522_9, 2017/10
Times Cited Count：4 Percentile：21.22(Physics, Fluids & Plasmas)In axisymmetric tokamak plasmas, effects of three-dimensional non-axisymmetric magnetic field perturbations caused by error fields etc. have attracted much attention from the view point of the control of the plasma performance and instabilities. Recent studies pointed out that there exists qualitative discrepancy in predicting the collisional viscosity driven by the perturbation between a theoretical bounce-averaged model and a global kinetic simulation. Clarifying the cause of the discrepancy by understanding the underlying mechanism is a key issue to establish a reliable basis for the NTV predictions. In this work, we perform two different kinds of global kinetic simulations for the NTV. As a result, it is first demonstrated that the discrepancy arises owing to the following two mechanisms related to the global particle orbit; (1) the effective magnitude of the perturbation becomes weak due to the loss of the resonant orbit, and (2) the phase mixing along the orbit arises and generates fine scale structures, resulting the damping of the NTV.
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：73.03(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.
integral invariant and momentum conservation in symplectic time integration of Hamiltonian partial differential equationsSasa, Narimasa
Journal of the Physical Society of Japan, 86(7), p.074006_1 - 074006_6, 2017/07
Times Cited Count：2 Percentile：20.86(Physics, Multidisciplinary)The momentum conservation law is investigated in numerical time evolutions of discretized Hamiltonian partial differential equations using symplectic integrators. Our investigation is based on the equivalence between the total momentum and the Poincare integral invariant of the system following our previous work. By introducing a Fourier interpolation method that is a canonical transformation, the total momentum of the system is shown to be an exact conserved quantity if the Hamiltonian possesses a discrete translational invariance and aliasing errors do not appear in the time evolutions. In addition, we perform numerical simulations that demonstrate the validity of our theoretical results under several conditions. Consequently, all symplectic integrators for discretized Hamiltonian partial differential equations are shown to inherit the property of the simultaneous conservation of the total momentum and approximated energy.
Takase, Kazuyuki; Ose, Yasuo*; Yoshida, Hiroyuki; Akimoto, Hajime; Satake, Shinichi*
Proceedings of International Conference on Jets, Wakes and Separated Flows (ICJWSF 2005), p.137 - 144, 2005/11
no abstracts in English
Yamaguchi, Yukichi; Imai, Yuki*; Tanabe, Fumiya
Hyuman Intafuesus Shimpojiumu 2005 Koen Rombunshu, p.779 - 782, 2005/09
In order to support of promoting deep system understanding of large complex system by various type of decision makers such as system operators, managers, regulation officers and citizen, a distanced education/training system on reactor simulator over internet DETRAS has been developed. With DETRAS, it is possible to operate a full scope reactor simulator, monitoring users' operation and give instructions over internet.
Takase, Kazuyuki; Yoshida, Hiroyuki; Akimoto, Hajime; Ose, Yasuo*
Nihon Konsoryu Gakkai Nenkai Koenkai 2005 Koen Rombunshu, p.231 - 232, 2005/08
no abstracts in English
Takase, Kazuyuki; Ose, Yasuo*; Yoshida, Hiroyuki; Akimoto, Hajime; Aoki, Takayuki*
Dai-24-Kai Nihon Shimyureshon Gakkai Taikai Happyo Rombunshu, p.161 - 164, 2005/07
no abstracts in English
Takase, Kazuyuki; Ose, Yasuo*; Yoshida, Hiroyuki; Akimoto, Hajime; Aoki, Takayuki*
Kashika Joho Gakkai-Shi, 25(Suppl.1), p.435 - 436, 2005/07
no abstracts in English
Takase, Kazuyuki
Nihon Kikai Gakkai Ryutai Kogaku Bumon Nyuzu Reta Nagare (Internet), 6 Pages, 2005/04
no abstracts in English
Takase, Kazuyuki; Yoshida, Hiroyuki; Ose, Yasuo*
Hai Pafomansu Komputingu To Keisan Kagaku Shimpojium (HPCS 2005) Rombunshu, P. 16, 2005/01
no abstracts in English
; Toward superconducting tunnel junctions and superconducting radiation detectors using thermal relaxation processIshida, Takekazu*; Wang, Z.*; Yotsuya, Tsutomu*; Machida, Masahiko
Kotai Butsuri, 40(1), p.51 - 67, 2005/01
no abstracts in English
Yoshida, Hiroyuki; Ose, Yasuo*; Takase, Kazuyuki; Akimoto, Hajime
Proceedings of 4th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-4), p.270 - 276, 2004/12
no abstracts in English
Takase, Kazuyuki; Yoshida, Hiroyuki; Ose, Yasuo*
Proceedings of 1st International Forum on Heat Transfer (IFHT 2004), p.207 - 208, 2004/11
no abstracts in English
Ose, Yasuo*; Takase, Kazuyuki; Yoshida, Hiroyuki
Proceedings of 1st International Forum on Heat Transfer (IFHT 2004), p.199 - 200, 2004/11
no abstracts in English
Takase, Kazuyuki; Yoshida, Hiroyuki; Ose, Yasuo*
Dai-23-Kai Nihon Shimyureshon Gakkai Taikai Happyo Rombunshu, p.121 - 124, 2004/06
no abstracts in English
