Search Results 1-20 of 487

  • WIND FLOW FIELDS AROUND BUILDINGS AND EDDY VISCOSITIES IN A LOW-TURBULENCE UNIFORM FLOW USING SGS MODELS FOR LES  [in Japanese]

    PHAM VAN PHUC , Ono Azusa , Nozu Tsuyoshi , Kikuchi Hirotoshi , Hibi Kazuki , Tamura Yukio

    … <p>A subgrid-scale model of traditional Smagorinsky Model (SM) and a model based on coherent structures called the Coherent-Structure Smagorinsky Model (CSM) have been applied to a large-eddy simulation to assess their performance in the prediction of wind flow field around buildings in comparison with PIV experimental results. …

    PROCEEDINGS OF NATIONAL SYMPOSIUM ON WIND ENGINEERING 25(0), 193-198, 2018

    J-STAGE 

  • Vertical Profiles of Temperature and Properties of Its Fluctuations for the Difference of Observational Environment  [in Japanese]

    Kawabata Yasuhiro , Yamamoto Akira , Shido Fumitake , Seino Naoko

    … <p>We studied temperature profiles near ground up to 2 m heights using very thin thermocouples in order to investigate the effect of surroundings on surface air temperature (1.5 m above the ground) measured by artificial ventilated thermometers in daytime on summer. … In addition, we investigated the properties of temperature fluctuations. …

    PROCEEDINGS OF NATIONAL SYMPOSIUM ON WIND ENGINEERING 25(0), 139-144, 2018

    J-STAGE 

  • Space–time 3D measurement of turbulence modulation with microbubbles by cross section laser imaging  [in Japanese]

    USHIYAMA Daiki , 朴 炫珍 , 田坂 裕司 , 村井 祐一

    … <p>In order to investigate interaction between microbubbles and coherent structure in a turbulent boundary layer, we visualized microbubbles injected into the boundary layer of a horizontal channel flow. … ,<i>w</i>) of microbubbles by PTV method. …

    The Proceedings of the Fluids engineering conference 2018(0), OS3-3, 2018

    J-STAGE 

  • Effects of Outer-layer Disturbance on Spatial Structure of Boundary-layer Turbulence Generated by PID Control and Linear Forcing  [in Japanese]

    Suto Hitoshi , Hattori Yasuo , Nakao Keisuke

    … <p>Large-eddy simulations (LESs) of a boundary layer flow were performed using a turbulence generation method based on linear forcing and proportional-integral-differential (PID) control. … The characteristics of flow and scalar fields generated by this method were similar to the presumed characteristics of an atmospheric surface-layer flow. …

    The Proceedings of the Thermal Engineering Conference 2018(0), 0133, 2018

    J-STAGE 

  • Exploration of secondary instability of artificially excited coherent structure in turbulent channel flow  [in Japanese]

    Takahashi Jun , Hirose Kazuya , Horiuchi Iori , Matsubara Masaharu

    The Proceedings of Conference of Hokuriku-Shinetsu Branch 2018.55(0), D041, 2018

    J-STAGE 

  • EFFECT OF COHERENT TURBULENCE STRUCTURE ON VERTICAL MASS TRANSPORT IN CANOPY OPEN-CHANNEL FLOWS WITH FLEXIBLE VEGETATIONS  [in Japanese]

    OKAMOTO Takaaki , SANJOU Michio

    …  Significant contributions of flow and turbulence to ecology related to aquatic benthic organism has been widely reported. … Aquatic vegetation is one of environmental variables that influence turbulence and the ecological condition of rivers. …

    Journal of Japan Society of Civil Engineers, Ser. A2 (Applied Mechanics (AM)) 74(1), 4-16, 2018

    J-STAGE 

  • Electron Surfing and Drift Accelerations in a Weibel-Dominated High-Mach-Number Shock.

    MATSUMOTO Yosuke , AMANO Takanobu , KATO Tsunehiko N , HOSHINO Masahiro

    … [ABSTRACT] How electrons get accelerated to relativistic energies in a high-Mach-number quasiperpendicular shock is presented by means of ab initio particle-in-cell simulations in three dimensions. … We found that coherent electrostatic Buneman waves and ion-Weibel magnetic turbulence coexist in a strong-shock structure whereby particles gain energy during shock surfing and subsequent stochastic drift accelerations. …

    Physical review letters 119(10), 105101-1-105101-5, 2017-09-08

    IR 

  • Three-dimensional transient rip currents: Bathymetric excitation of low-frequency intrinsic variability

    Uchiyama Yusuke , McWilliams James C. , Akan Cigdem

    … The ROMS-WEC model [Uchiyama et al., 2010] based on an Eulerian wave-averaged vortex-force asymptotic theory of McWilliams et al. … The 3-D rip currents are substantially depth-dependent due to the vertical recirculation, composed of pairs of counter-rotating longitudinal overturning roll cells that promote surface convergence. …

    Journal of Geophysical Research: Oceans 122(7), 5826-5849, 2017-07

    IR 

  • Wind Pressure Distributions on Buildings obtained by LES with SGS models and Courant Numbers  [in Japanese]

    PHUC PHAM VAN , Nozu Tsuyoshi , Kikuchi Hirotoshi , Hibi Kazuki , Tamura Yukio

    … Numerical simulations using two types of subgrid-scale (SGS) models, Standard Smagorinsky model (SM model) and Coherent Structure Smagorinsky model (CSM model) for Large Eddy Simulation (LES) with different Courant numbers, were carried in a low-turbulence uniform flow for the rectangular and setback buildings. …

    Summaries to Technical Papers of Annual Meeting, Japan Association for Wind Engineering 2017(0), 147-148, 2017

    J-STAGE 

  • Large Eddy Simulation of Flow Field Above and Within Urban Canopy Using SGS Model Based on Turbulent Structures  [in Japanese]

    Ono Azusa , Van Pham Phuc

    … In this study, Large Eddy Simulation (LES) is performed to investigate the validity of coherent-structure Smagorinsky model (CSM), SGS model based on the coherent structures in grid-scale flow fields proposed by Kobayashi. … Spatial distribution of model coefficient estimated by CSM show larger value above urban canopy and smaller value behind the building than that of SM, given as 0.01. …

    PROCEEDINGS OF NATIONAL SYMPOSIUM ON WIND ENGINEERING 24(0), 67-72, 2016

    J-STAGE 

  • Influence of vortex dynamics and structure on turbulence statistics at large scales

    Yoshimatsu Katsunori , Anayama Koujiro , Kaneda Yukio

    … The question whether the vortex dynamics and structure at small scales have significant influence on the statistics at large scales is addressed on the basis of quantitative comparison of two turbulent fields. … One is a reference field generated by direct numerical simulation of turbulence of an incompressible fluid obeying the Navier-Stokes (NS) equation in a periodic box. …

    Physics of Fluids 27(5), 055106, 2015-05

    IR 

  • Computational Method for Micrometeorological Field usign Coherent-structure Smagorinsky Model  [in Japanese]

    Inoue Minoru

    … The diffusion phenomena of heat and pollutants caused by turbulent flows in the non-isothermal field is one of the important phenomena concerned with local heavy rain or high levels of air pollution. … The large eddy simulation (LES) which can analyze the turbulence structures in the non-isothermal field is considered as one of the effective means for investigating those phenomena.<br> …

    Proceeding of Annual Conference 28(0), 100011, 2015

    J-STAGE 

  • 1511 Structural dependence of lifetime of localized turbulence in plane channel flow  [in Japanese]

    KANAZAWA Takahiro , SHIMIZU Masaki , KAWAHARA Genta

    … Turbulent flow near a wall is autonomously driven by coherent structures. … By sudden disappearance of these structures, turbulence can't be sustained and laminarization is occurred. …

    The Proceedings of the Fluids engineering conference 2015(0), _1511-1_-_1511-3_, 2015

    J-STAGE 

  • Stability Dependence and Diurnal Change of Large-Scale Turbulence Structures in the Near-Neutral Atmospheric Boundary Layer Observed from a Meteorological Tower

    Horiguchi Mitsuaki , Hayashi Taiichi , Adachi Ahoro , Onogi Shigeru

    … Based on the analysis of observations from a 213-m tall meteorological tower at Tsukuba, Japan, we have investigated the favourable conditions for the predominant existence of large-scale turbulence structures in the near-neutral atmospheric boundary layer (ABL). …

    Boundary-Layer Meteorology 151(2), 221-237, 2014-05

    IR 

  • Local Wind Pressure Distributions on a Building With a Setback in Low-turbulence Uniform Flow Using SGS Models for LES  [in Japanese]

    Pham Van Phuc , Nozu Tsuyoshi , Kikuchi Hirotoshi , Hibi Kazuki , Tamura Yukio

    … Large negative pressures are observed experimentally on the sidewall of a building with a setback in local pressure zone. … Numerical simulations using two types of SGS models, Standard Smagorinsky model and Coherent Structure Smagorinsky model (CSM model) for LES with meshes in different resolutions are carried in low-turbulence uniform flow. …

    PROCEEDINGS OF NATIONAL SYMPOSIUM ON WIND ENGINEERING 23(0), 463, 2014

    J-STAGE 

  • TURBULENT STRUCTURE IN OPEN CHANNEL FLOW WITH FLEXIBLE VEGETATION MODEL  [in Japanese]

    WATANABE Katsutoshi , ABE Ikki , GAMOU Ryou

    … Characteristics of turbulent structure of open channel flow with flexible vegetation model on the bottom wall were investigated using velocity measurements and flow visualization techniques. …

    Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering) 70(4), I_709-I_714, 2014

    J-STAGE 

  • EXPERIMENTAL STUDY ON TRANSITION AND DECAYING PROCESS OF TURBULENCE STRUCTURE BEHIND A FINITE VEGETATION PATCH AND STEADY WAKE REGION  [in Japanese]

    OKAMOTO Takaaki , FUJIMOTO Yuta , AOKI Seita , TODA Keiichi , SANJOU Michio

    … The effect of the vegetation patch on the downstream flow and turbulence is investigated, including the effect of a length of a vegetation-patch on the development of mean and turbulence characteristics. … Turbulence measurements were intensively conducted in partly vegetated-open-channel flows using Particle Image Velocimetry (PIV). …

    Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering) 70(4), I_685-I_690, 2014

    J-STAGE 

  • REFINEMENT OF A DEPTH-AVERAGED RANS MODEL FOR OPEN CHANNEL FLOWS WITH SHEAR INSTAILITY  [in Japanese]

    KIMURA Ichiro , HOSODA Takashi , IWATA Michiaki , ONDA Shinichiro

    … We developed a new RANS turbulence model for simulating flows with large scale vortex formations due to the shear instability. … In this model, the eddy viscosity is set locally larger where the turbulence level is increased due to vortex shedding. … The eddy viscosity is expressed by the summation of two terms, i.e., (i) effect of turbulence in a base flow and (ii) contribution by the vortex formations. …

    Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering) 70(4), I_799-I_804, 2014

    J-STAGE 

  • Randomness representation in turbulent flows with Kolmogorov complexity (In turbulence wedge developed from a single roughness element on a flat plate)  [in Japanese]

    ICHIMIYA Masashi , NAKAMURA Ikuo , HARA Tatsuhiko

    … The complexity or randomness was examined with the aid of Kolmogorov complexity for the flow about a turbulence wedge developed from a single roughness element on a flat plate. … Although the AK variation of fluctuating velocity and that of its time derivative do not completely agree with that of the fluctuating velocity and the intermittency factor, they do roughly. …

    Transactions of the JSME (in Japanese) 80(813), FE0117-FE0117, 2014

    J-STAGE 

  • Large eddy simulation of weakly compressible turbulent flows around an airfoil

    HAN Changhwa , KAJISHIMA Takeo

    … The purpose of this study is to develop a numerical method for turbulent flows at low Mach number range. … To account for the weak compressibility, we modify the time marching method of the usual incompressible scheme which is based on the elliptic equation for pressure. …

    Journal of Fluid Science and Technology 9(4), JFST0063-JFST0063, 2014

    J-STAGE 

Page Top