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Zhang, H.*; Umehara, Yutaro*; Yoshida, Hiroyuki; Mori, Shoji*
International Journal of Heat and Mass Transfer, 211, p.124253_1 - 124253_13, 2023/09
Times Cited Count：3 Percentile：59.37(Thermodynamics)Zhang, H.*; Mori, Shoji*; Hisano, Tsutomu*; Yoshida, Hiroyuki
International Journal of Multiphase Flow, 159, p.104342_1 - 104342_15, 2023/02
Times Cited Count：5 Percentile：65.31(Mechanics)Okagaki, Yuria; Yonomoto, Taisuke; Ishigaki, Masahiro; Hirose, Yoshiyasu
Fluids (Internet), 6(2), p.80_1 - 80_17, 2021/02
Saito, Shimpei*; De Rosis, A.*; Fei, L.*; Luo, K. H.*; Ebihara, Kenichi; Kaneko, Akiko*; Abe, Yutaka*
Physics of Fluids, 33(2), p.023307_1 - 023307_21, 2021/02
Times Cited Count：34 Percentile：98.32(Mechanics)A Boiling phenomenon in a liquid flow field is known as forced-convection boiling. We numerically investigated the boiling system on a cylinder in a flow at a saturated condition. To deal with such a phenomenon, we developed a numerical scheme based on the pseudopotential lattice Boltzmann method. The collision was performed in the space of central moments (CMs) to enhance stability for high Reynolds numbers. Furthermore, additional terms for thermodynamic consistency were derived in a CMs framework. The effectiveness of the model was tested against some boiling processes, including nucleation, growth, and departure of a vapor bubble for high Reynolds numbers. Our model can reproduce all the boiling regimes without the artificial initial vapor phase. We found that the Nukiyama curve appears even though the focused system is the forced-convection system. Also, our simulations support experimental observations of intermittent direct solid-liquid contact even in the film-boiling regime.
Shen, X.*; Schlegel, J. P.*; Hibiki, Takashi*; Nakamura, Hideo
Nuclear Engineering and Design, 333, p.87 - 98, 2018/07
Times Cited Count：11 Percentile：32.69(Nuclear Science & Technology)Uchibori, Akihiro; Watanabe, Akira*; Takata, Takashi; Ohshima, Hiroyuki
Journal of Nuclear Science and Technology, 54(10), p.1036 - 1045, 2017/10
Times Cited Count：5 Percentile：44.54(Nuclear Science & Technology)To evaluate a sodium-water reaction phenomenon in a steam generator of sodium-cooled fast reactors, a computational fluid dynamics code SERAPHIM, in which a compressible multicomponent multiphase flow with sodium-water chemical reaction is computed, has been developed. The original SERAPHIM code is based on the difference method. In this study, unstructured mesh-based numerical method was developed to advance a numerical accuracy for the complex-shaped domain including multiple heat transfer tubes. Numerical analysis of an underexpanded jet experiment was performed as part of validation of the unstructured mesh-based numerical method. The calculated pressure profile showed good agreement with the experimental data. Applicability of the numerical method for the actual situation was confirmed through the analysis of water vapor discharging into liquid sodium. The effect of use of the unstructured mesh was also investigated by the two analyses using structured and unstructured mesh.
Guo, L.*; Morita, Koji*; Tobita, Yoshiharu
Journal of Nuclear Science and Technology, 53(2), p.271 - 280, 2016/02
Times Cited Count：7 Percentile：55.03(Nuclear Science & Technology)Kato, Yuki; Yoshida, Hiroyuki; Yokoyama, Ryotaro*; Kanagawa, Tetsuya*; Kaneko, Akiko*; Monji, Hideaki*; Abe, Yutaka*
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 8 Pages, 2015/05
Ito, Kei; Kunugi, Tomoaki*; Ohno, Shuji; Kamide, Hideki; Ohshima, Hiroyuki
Journal of Computational Physics, 273, p.38 - 53, 2014/09
Times Cited Count：17 Percentile：71.23(Computer Science, Interdisciplinary Applications)Yoshida, Hiroyuki; Nagatake, Taku; Takase, Kazuyuki; Kaneko, Akiko*; Monji, Hideaki*; Abe, Yutaka*
Mechanical Engineering Journal (Internet), 1(4), p.TEP0025_1 - TEP0025_11, 2014/08
Ebihara, Kenichi
JAERI-Research 2005-004, 121 Pages, 2005/03
JAERI-Research-2005-004.pdf:19.79MB
This report is the JAERI's report version of the doctor thesis by the author. In this report, first, the validity and usefulness of the application of the two-phase fluid model of the lattice-gas method and the lattice Boltzmann method(LBM) are examined. On the basis of the examination, next, the horizontal stratified two-phase flow that is the fundamental and important flow is simulated by the HCZ model which is one of the two-phase fluid model of the LBM. It is seen that the interfacial growth of the HCZ model satisfies the Kelvin-Helmholtz instability theory and reproduces the theoretical two-phase flow regime map of Taitel and Dukler(T-D map). It is found that more superficial flow velocity of the rare phase is necessary in the channel with the narrow width. The HCZ model can also simulate the droplet generation accompanying more complex interfacial phenomena and reproduce the experimental correlation of Ishii and Grolmes in the range of the distribution of the experimental data.
Takase, Kazuyuki; Yoshida, Hiroyuki; Ose, Yasuo*; Akimoto, Hajime
WIT Transactions on Engineering Sciences, Vol.50, p.183 - 192, 2005/00
no abstracts in English
Miyato, Naoaki; Kishimoto, Yasuaki; Li, J.
Physics of Plasmas, 11(12), p.5557 - 5564, 2004/12
Times Cited Count：116 Percentile：95.02(Physics, Fluids & Plasmas)Global characteristics of the coupled system of zonal flows and electromagnetic ion temperature gradient driven turbulence in tokamak plasmas are investigated using a global electromagnetic Landau fluid code. Zonal flow behavior changes with the safety factor 
. In a low region stationary zonal flows are excited and suppress the turbulence effectively. Coupling between zonal flows and poloidally asymmetric pressure perturbations due to a geodesic curvature makes the zonal flows oscillatory in a high region. Energy transfer from the oscillatory zonal flows to the turbulence via the poloidally asymmetric pressure perturbations is identified. Therefore in the high region where the zonal flows are oscillatory, the zonal flows cannot quench the turbulence and turbulent transport is not suppressed completely. As for the zonal flow behavior, it is favorable for confinement improvement to make the low region where the stationary zonal flows are dominant in tokamak plasmas.
Ebihara, Kenichi; Watanabe, Tadashi
Proceedings of 2004 ASME International Mechanical Engineering Congress and Exposition (IMECE '04) (CD-ROM), 9 Pages, 2004/11
This paper describes the numerical simulation of the interfacial growth of the stratified wavy two-phase flow in the horizontal rectangular channel. The influence of the channel width upon the growth of the interfacial wave was evaluated by the several simulations for the different channel width. The numerical simulation model adopted in this paper is a one-component two-phase fluid model of the lattice Boltzmann method. The wave growth was observed and the dimensionless numbers that characterize the two-phase flow state were measured during the computations. The relation between the wave growth and the dimensionless numbers, which characterize the flow state, was compared with that in the flow pattern map proposed by Taitel and Dukler. It was verified in the case of the wide channel width that the simulated relation was almost in agreement with that in the flow pattern map. It was shown that the narrower the channel width became, the more mass flow rate of the rare phase the interfacial growth needed and the obtained relation deviated from that in the flow pattern map.
Ebihara, Kenichi
Tsukuba Daigaku Daigakuin Shisutemu Joho Kogaku Kenkyuka Hakase Gakui Rombun, 134 Pages, 2004/09
In this thesis, first the liquid-gas models of the lattice method are examined by applying them to two-phase flow simulations. Next the liquid-gas model(the HCZ model) of the lattice Boltzmann method is applied to the three-dimensional simulation of the horizontal stratified two-phase flow. The following results are obtained. (1)The two- and three- dimensional interface simulated by the HCZ model satisfies the Kelvin-Helmholtz instability theory. (2)In the simulation of the interfacial growth in the rectangular channel, it is found that the relation between the interfacial growth and the flow state is in agreement with the flow regime map proposed theoretically by Taitel and Dukler. (3)It is also found that the three dimensionality becomes remarkable and the interfacial growth needs more flow rate of the rare phase than that of the theoretical flow regime map when the channel width is narrower. (4)In the droplet creation simulation, it is found that the relation between the droplet creation and the flow state simulates the experimental correlation proposed by Ishii and Grolmes.
Hattori, Hirofumi*; Sato, Hiroshi; Nagano, Yasutaka*
Nihon Kikai Gakkai Rombunshu, B, 70(696), p.1919 - 1926, 2004/08
no abstracts in English
Ebihara, Kenichi; Watanabe, Tadashi
Nihon Kikai Gakkai Rombunshu, B, 70(694), p.1393 - 1399, 2004/06
The horizontal stratified two-phase flow in the rectangular pipe whose width in smaller than the height is simulated by the one-component two-phase lattice Boltzmann method. The interfacial growth between two phases is measured for three cases with the different pipe width and the measured dimensionless number charactering the two-phase flow is compared with the flow regime map proposed by Taitel and Dukler. It is found that the boundary separating the interfacical growth from the non-growth which is obtained by the simulations is larger in the flow regime map when the pipe width is narrower.
Li, J.; Kishimoto, Yasuaki
Physics of Plasmas, 11(4), p.1493 - 1510, 2004/04
Times Cited Count：59 Percentile：85.33(Physics, Fluids & Plasmas)The electron temperature gradient (ETG) driven turbulence in tokamak core plasmas is numerically investigated based on three-dimensional gyrofluid model with adiabatic ion response. Attentions are focused on the zonal flow dynamics in ETG fluctuations and the resultant electron heat transport. A high electron energy confinement mode is found in the weak magnetic shear regime, which is closely relevant with self-organization behavior of turbulence through the enhanced zonal flow dynamics rather than the weak shear stabilization of ETG fluctuations. It is demonstrated that the weak shear is favorable for the enhancement of zonal flows in ETG turbulence.
Li, J.; Kishimoto, Yasuaki
Physical Review Letters, 89(11), p.115002_1 - 115002_4, 2002/09
Times Cited Count：32 Percentile：77.34(Physics, Multidisciplinary)Interaction between small-scale zonal flows and large-scale turbulence is investigated. The key mechanism is identified as radially non-local mode coupling. Fluctuating energy can be non-locally transferred from the unstable longer to stable or damped shorter wavelength region, so that turbulence spectrum is seriously deformed and deviated from the nonlinear power law structure. Three-dimensional gyro-fluid ion temperature gradient (ITG) turbulence simulations show that an ion transport bursting behavior is consistently linked to the spectral deformity with the causal role of ITG-generated zonal flows in tokamak plasmas.
Li, J.; Kishimoto, Yasuaki
Physics of Plasmas, 9(4), p.1241 - 1254, 2002/04
Times Cited Count：37 Percentile：72.54(Physics, Fluids & Plasmas)Zonal flows can be generated by drift wave turbulence through the nonlinear interactions. 3-D gyrofluid simulations show that in a turbulent system driven by electrostatic sheared slab electron temperature gradient(ETG) modes, the excitation of zonal flows is a slower process that indicates the amplitudes grow up approximately proportionally to time. The zonal flows are very weak comparing with the background turbulence and hardly work for suppressing the turbulent electron heat transport. The dynamics of zonal flows is numerically explored through starting zonal flow component in the quasi-steady state.
