Search Results 1-20 of 1170

  • Analysis of Aerodynamic Effects of Windbreaks on Transport of Air Pollutants in and around Forests  [in Japanese]

    Ichikawa Yoichi , Tsuyuki Keisuke , Komoda Naoto , Miyamoto Kenta , Hirohata Tomoya , Nakasono Mai , Seki Koichi , Mouri Hideaki , Morinaga Takeshi

    <p>グリーンインフラは大気汚染の緩和策の一つとして注目されている。森林による大気質の改善について、樹木への沈着や樹木の吸着の観点からの研究は多い。しかし、大気汚染物質の輸送におよぼす樹木の流体力学的効果については、これまで沿道の大気汚染緩和に着目され、森林を対象とした研究事例はほとんどない。そこで本研究では森林を対象に風洞実験によって流体力学的効果を解析した。実験に用いた樹木模型の空 …

    Journal of Japan Society for Atmospheric Environment / Taiki Kankyo Gakkaishi 55(2), 50-59, 2020

    J-STAGE 

  • Time development of energy spectrum in rotating inhomogeneous turbulence accompanied with helicity injection  [in Japanese]

    INAGAKI Kazuhiro

    <p>ヘリシティの空間的に非一様な分布を伴った回転乱流において,統計平均した速度分布が自発的に形成されることが知られている.本研究では速度場の空間的な輸送だけでなく,運動エネルギーの波数空間におけるスケール間の輸送という観点で現象を調べる.空間に関して狭い領域に乱流のエネルギーやヘリシティを注入する周期箱系における回転乱流の数値計算を実行する.その結果,平均速度分布が時間発展する一方で …

    SEISAN KENKYU 72(1), 37-40, 2020

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  • Numerical simulation of grid turbulence in an unstably stratified fluid  [in Japanese]

    KOYAMA Shoji

    <p>乱流モデルを用いて温度成層を伴う格子乱流の数値計算を行う.一般的な格子乱流の場合,温度成層とは安定成層であることがほとんどであるが,本研究では,Thoroddsen et al.(1998)の風洞実験による不安定な線形温度分布を持った流体が正方格子を通過する乱流の統計量を調べる.使用する乱流モデルは,熱拡散係数の輸送方程式を解く独自のモデルである.結果は,その提案したモデルでも実 …

    SEISAN KENKYU 72(1), 31-35, 2020

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  • Magnetoclinicity effect in compressible magnetohydrodynamic turbulence  [in Japanese]

    YOKOI Nobumitsu

    <p>多重スケールくりこみ摂動展開の方法で,強い圧縮性をもつ電磁流体乱流の乱流相関を解析した結果を示す.平均磁場の誘導方程式での乱流効果を表す乱流起電力には,非圧縮性で見られる通常のダイナモ諸項に加えて,圧縮性に固有の項が現れ,輸送係数が密度分散(密度ゆらぎの大きさ)で表される.特に,平均の密度勾配と磁場の傾きによる項があり,「傾磁場効果」(magnetoclinicity)と名付けら …

    SEISAN KENKYU 72(1), 25-29, 2020

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  • Kinetic Theory of Parallel Momentum Transport due to Collisionless Electromagnetic Turbulence in Slab Geometry

    Li Yang , Gao Zhe , Li Jiquan

    Journal of the Physical Society of Japan 88(8), 084501-1-6, 2019-08

    DOI 

  • Persistence of Ion Temperature Gradient Turbulent Transport at Finite Normalized Pressure

    Ishizawa A. , Urano D. , Nakamura Y. , Maeyama S. , Watanabe T.-H.

    … Plasma β dependence of electromagnetic turbulent transport is investigated by means of gyrokinetic simulations with self-consistent change of the equilibrium magnetic field. … It is found that energy transport due to ion-temperature-gradient (ITG) driven turbulence does not decrease with increasing β; …

    Physical Review Letters (123), 2019-07-10

    IR 

  • Residual Transport of Suspended Material by Tidal Straining over the Sloping Continental Shelf  [in Japanese]

    Endoh Takahiro , Kirstin Schulz , Yoshikawa Yutaka , Matsuno Takeshi , Wakata Yoshinobu , Lee Keunjong , Lars Umlauf

    海底斜面近傍で,背景場の密度成層の斜面への射影として生じる水平勾配が,潮汐流の鉛直シアーによる変形"tidalstraining"を受けることで,流れが斜面を駆け上る時に斜面下方の高密度水が乗り上げて成層が不安定化し,斜面を駆け下る時に斜面上方の低密度水が乗り上げて成層が安定化する潮汐周期の変動が存在することが,夏季の東シナ海陸棚域における乱流微細構造観測によって初めて明らかとなった.乱流クロージ …

    Bulletin on Coastal Oceanography 57(1), 31-37, 2019

    J-STAGE 

  • Diapycnal Mixing Processes and Their Impacts Along the Kuroshio from its Upstream to the Kuroshio Extension  [in Japanese]

    Nagai Takeyoshi

    日本沿岸を流れる黒潮は,流域の気象や海象,生態系に多大な影響を及ぼす.これまでの研究によって,北大西洋のガルフストリームと同様に,表層で貧栄養である黒潮は,その亜表層では栄養塩を下流へ運ぶ栄養塩ストリームであることが明らかとなっている.本稿では,この黒潮の上流から下流である黒潮続流で発生する重要な鉛直混合過程と,その影響について特に黒潮栄養塩ストリームからの栄養塩供給に関して考察を試みた.これまで …

    Bulletin on Coastal Oceanography 57(1), 43-58, 2019

    J-STAGE 

  • Role of the hierarchy of vortices in turbulent transport  [in Japanese]

    Goto Susumu , Oka Sunao , Motoori Yutaro

    The Proceedings of Mechanical Engineering Congress, Japan 2019(0), J05102, 2019

    J-STAGE 

  • Numerical Analysis of Two-Phase Flow in a Micro-Hydraulic Turbine

    Chen Tiejun , Sun Shuaihui , Pang Ye , Guo Pengcheng

    … Aiming at improving the hydraulic efficiency of the micro-turbine, the three-dimensional transient two-phase flow model which adopts the shear-stress-transport (SST) model as turbulence model and Eulerian-Eulerian model as two-phase flow model with the commercial code ANSYS-CFX was established and solved to study the two-phase flow characteristics of the micro-hydraulic turbine with fixed guide vane openings under different gas volume fraction (GVF). …

    International Journal of Fluid Machinery and Systems 12(4), 430-438, 2019

    J-STAGE 

  • MODIFICATION OF SEA SURFACE ABSORPTION IN GAUSSIAN PLUME MODEL FOR ATMOSPHERIC DISPERSION IN NUCLEAR ACCIDENT

    Wu Siyuan , Ma Yuanwei , Wang Dezhong , Gu Weiguo

    … Moreover, the turbulence transport near sea surface affect also the diffusion process. … So in order to make the atmospheric diffusion calculation model suitable for the marine environment, this paper revised the Gaussian plume model by taking account of the influence of absorption of seawater, sea waves and the influence of turbulence transport. …

    The Proceedings of the International Conference on Nuclear Engineering (ICONE) 2019.27(0), 2175, 2019

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  • Numerical Study on Scalar Transport in Single-Square-Grid-generated Turbulence

    Yu Jihong , Sakai Yasuhiko , Ito Yasumasa , Iwano Koji , Hayase Toshiyuki

    The Proceedings of Conference of Tokai Branch 2019.68(0), 216, 2019

    J-STAGE 

  • Study on scale-by-scale transport mechanism for energy and scalar in grid-generated turbulence  [in Japanese]

    HIGAKI Shuichi , ITO Yasumasa , SAKAI Yasuhiko , IWANO Koji

    The Proceedings of Conference of Tokai Branch 2019.68(0), 215, 2019

    J-STAGE 

  • FUNDAMENTAL STUDY ON LOCAL GAS TRANSFER PROPERTY IN OPEN-CHANNEL TURBULENCE  [in Japanese]

    SANJOU Michio , OKAMOTO Takaaki

    <p> 開水路のガス輸送機構の解明は自然河川,水処理施設,水産用水路などの水質保全において,非常に重要である.特にガス輸送速度の信頼性の高い評価モデルの構築が急務である.古くから様々な物理モデルが考案されているが,マクロな計測結果や考察に基づくものがほとんどで,局所的な特性については未解明である.そこで本研究では濃度境界層厚さに関する支配方程式を導くとともに,極小径のDOプローブを用い …

    Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering) 75(1), 100-111, 2019

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  • The unsteady simulation for turbulent cavitating flow around a hydrofoil at a low angle of attack  [in Japanese]

    OKABAYASHI Kie , INAOKA Takuya , LUO Wenyang , KAJISHIMA Takeo

    … For LES, the subgrid scale (SGS) eddy viscosity was determined by solving the transport equation of SGS kinetic energy. … The reproducibility of the cavitation characteristics of the hydrofoil was improved in comparison with that by previous Reynolds-averaged turbulence models. …

    Transactions of the JSME (in Japanese) 85(876), 19-00124-19-00124, 2019

    J-STAGE 

  • Effects of the Plasma Blob Nonlinear Formation/Transport on Impurity Transport in the SOL Regions

    MAEDA Tomoyuki , HASEGAWA Hiroki , ISHIGURO Seiji , HOSHINO Kazuo , HATAYAMA Akiyoshi

    … <p>The purpose of this study is to make clear the effects of the plasma blob on the impurity transport in the Scrape-Off Layer (SOL) regions. … By using the two-dimensional (2D) interchange turbulence model with plasma transport along magnetic field line, we have simulated the plasma blob formation and transport in the SOL regions. …

    Plasma and Fusion Research 14(0), 3403133-3403133, 2019

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  • Shape optimization of a bended film-cooling hole to enhance cooling effectiveness

    KIM Jun-Hee , KIM Kwang-Yong

    … The turbulence was modeled using a shear stress transport model. …

    Journal of Thermal Science and Technology 14(1), JTST0011-JTST0011, 2019

    J-STAGE 

  • Simultaneous Optimization of Impeller and Volute of a Single-channel Pump for Wastewater Treatment

    Kim Jin-Hyuk , Ma Sang-Bum , Choi Young-Seok , Kim Kwang-Yong

    … Steady and unsteady Reynolds-averaged Navier–Stokes equations were solved with the shear stress transport turbulence model as the turbulence closure model using tetrahedral grids to analyze the internal flow in the single-channel pump. …

    International Journal of Fluid Machinery and Systems 12(2), 99-108, 2019

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  • Transport Simulation for Helical Plasmas by use of Gyrokinetic Transport Model

    TODA Shinichiro , NAKATA Motoki , NUNAMI Masanori , ISHIZAWA Akihiro , WATANABE Tomo-Hiko , SUGAMA Hideo

    … <p>Transport simulation for the electron and ion temperature profiles is performed in helical plasmas by using the heat diffusivity models and the quasilinear flux models [S. … Plasmas <b>26</b>, 012510 (2019)] for the electron and ion heat turbulent transport. … The turbulent transport for the nonlinear simulation results can be evaluated by these models. …

    Plasma and Fusion Research 14(0), 3403061-3403061, 2019

    J-STAGE 

  • Wildfires Modelling: Short Overview, Challenges and Perspectives

    MORVAN Dominique

    … The spectra of length scales (idem for the time scales) associated to wildfires is very large (ranged between 100 μm for the flame depth to several 100 kms for the plume trajectory), coupling many non-linear physical phenomena such as the atmospheric turbulence in interaction with the vegetation and the flame, the degradation of the vegetation, the radiation heat transfer associated to the production and the transport of soot particles from the burning zone, and so on ... …

    Journal of the Combustion Society of Japan 61(196), 120-125, 2019

    J-STAGE 

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