研究者詳細 - 鈴木　博貴

Validation Scheme for Small Effect of Wind Tunnel Blockage on Decaying Grid-Generated Turbulence 査読

Local Wall Shear Stress Measurements with a Thin Plate Submerged in the Sublayer in Wall Turbulent Flows 査読

Hua Dan, Hiroki Suzuki, Shinsuke Mochizuki

Experiments in Fluids 58 124 - (11 pages) 2017年8月

Numerical investigation using an exact solution of the effects of non-solenoidality of the viscous terms on the incompressible flow 査読

Hiroki Suzuki, Shingo Hattori, Shinsuke Mochizuki

Journal of Fluid Science and Technology 12 ( 1 ) 16-00257 - (13 pages) 2017年

Simple Model of Decay of Homogeneous Turbulence Affected by Weak Fluid Acceleration 査読

Hiroki Suzuki, Shinsuke Mochizuki

(全文査読付) Proceedings of the 20th Australasian Fluid Mechanics Conference Paper No.411 - (4 pages) 2016年12月

Basis Study on the Output-Voltage Variation of Constant-Temperature Anemometry at Freestream Velocity 査読

Hiroki Suzuki, Shingo Hattori, Shinsuke Mochizuki, Yutaka Hasegawa

Advanced Experimental Mechanics 1 36 - 41 2016年8月

Effect of Fluid Acceleration due to Area Reduction of a Wind Tunnel on Temporally and Spatially Decaying Grid Turbulence 査読

Hiroki Suzuki, Shinnosuke Matsuo, Shinsuke Mochizuki, Yutaka Hasegawa

Advanced Experimental Mechanics 1 15 - 22 2016年8月

Hiroki Suzuki, Shinsuke Mochizuki, Yutaka Hasegawa

Journal of Fluid Science and Technology 11 ( 3 ) 16-00195 - (13 pages) 2016年7月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人日本機械学会

<p>This paper proposes a validation scheme for the effect of wind tunnel blockage on decaying grid-generated turbulence. This validation scheme was derived from the governing equations of the k-∈ model. Analytical solutions for the validation scheme were derived by introducing a model of the difference between the rate of change of the effect of fluid acceleration on the turbulent kinetic energy and that of the effect on its dissipation. The derived solutions include a decay exponent that excludes the acceleration effect, a parameter characterizing the acceleration, the initial anisotropy, and the model coefficient of the k-∈ model, and can be quantified by parameters which can be known. The physical meaning of the model was clarified. The derived solutions and model were confirmed to be accurate through numerical simulation. An equation for the decay exponent, which is also affected by the fluid acceleration, was developed using the derived solutions. This scheme was applied to the examination of the reduced fluid acceleration effect in a moderate-sized wind tunnel to measure the grid-generated turbulence. The fluid acceleration effect in the wind tunnel was confirmed to be small using the derived equations. The decay characteristics of the grid-generated turbulence in the wind tunnel were measured and were found to agree with those obtained in previous experiments.</p>

DOI： 10.1299/jfst.2016jfst0012

自動車用送風機の電力回生に関する研究（風車による車両冷却系空気抵抗への影響）査読

その他リンク： https://jlc.jst.go.jp/DN/JLC/20023288926?from=CiNii

Shinsuke Mochizuki, Hiroki Suzuki, Hitoshi Tokunaga, Takatsugu Kameda

(全文査読付) Proceedings of the 5th International Conference on Jets, Wakes and Separated Flows (ICJWSF2015) 185 ( 1 ) 317 - 324 2016年

Mixing and diffusion in regular/fractal grid turbulence

Yasuhiko Sakai, Koji Nagata, Hiroki Suzuki, Yasumasa Ito

CISM International Centre for Mechanical Sciences, Courses and Lectures 568 17 - 73 2016年

Research of Electric Power Regeneration using Automotive Cooling Fan (Improvement of Fan Efficiency by Diffuser) 査読

Yoshitaka Wagayama, Shinichi Oda, Yutaka Hasegawa, Hiroki Suzuki, Tatsuo Ushijima

(全文査読付) Proceedings of the International Symposium on EcoTopia Science 2015 Paper No. 1035 - (1 page) 2015年12月

Study on Pitch Motion Optimization of Wing-Stroke Wind Turbine 査読

Hironori Nakano, Yutaka Hasegawa, Hiroki Suzuki, Tatsuo Ushijima

(全文査読付) Proceedings of the International Symposium on EcoTopia Science 2015 Paper No. 1028 - (1 page) 2015年12月

A Small Wind Tunnel with Lower Fluid Acceleration 査読

Shinnosuke Matsuo, Hiroki Suzuki, Yutaka Hasegawa, Tatsuo Ushijima, Shinsuke Mochizuki

(全文査読付) Proceedings of the 10th International Symposium on Advanced Science and Technology in Experimental Mechanics Paper No.A111 - (6 pages) 2015年11月

Fundamental Study on the Temporal Variation of CTA Calibration Curves 査読

Hiroki Suzuki, Shinsuke Mochizuki, Yutaka Hasegawa

(全文査読付) Proceedings of the 10th International Symposium on Advanced Science and Technology in Experimental Mechanics Paper No.A112 - (6 pages) 2015年11月

織田信一, 長谷川豊, 鈴木博貴, 牛島達夫, 大矢英樹

日本機械学会論文集 81 ( 830 ) 14-00169 - (16 pages) 2015年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：The Japan Society of Mechanical Engineers

This work aims at developing a new fan-turbine that operates as a cooling fan at a low vehicle speed and operates as a wind turbine at a high vehicle speed to generate electric power. The present paper reports the influence of a wind turbine on air resistance through a vehicle cooling system. We have developed a method to measure air resistance by using a general-purpose facility and the following results have been provided. The wind turbine operation reduces air resistance through the cooling system and regenerates electric power simultaneously. Furthermore we have confirmed the influence of the wind turbine on air resistance through the vehicle cooling system by using a CFD analysis.

DOI： 10.1299/transjsme.14-00691

自動車用送風機の電力回生に関する研究（高ソリディティ翼による実車での風車出力向上）査読

織田信一, 長谷川豊, 鈴木博貴, 牛島達夫, 大矢英樹

日本機械学会論文集 81 ( 829 ) 15-00042 - (12 pages) 2015年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：The Japan Society of Mechanical Engineers

This work aims at developing a new cooling fan for vehicle engine. This fan can operate as a cooling fan at low vehicle speed. At high vehicle speed, however, the fan is rarely used as a cooling fan. Therefore the fan can be used as a wind turbine, which generates electric power. In the previous report we had confirmed the effect of S-Shaped blade profile on the wind turbine efficiency by CFD analysis and the experiments. The present paper reports the enhancement of wind turbine power by installing high solidity rotor on a vehicle. High solidity rotor can increase the wind turbine efficiency and receive more input power due to the increased rate of the rotor resistance to the total resistance through the cooling system, although the air flow rate through the system decreases. We confirmed by the estimation and the actual vehicle test that the high solidity rotor can regenerate more electric power than the original low solidity rotor.

DOI： 10.1299/transjsme.15-00042

自動車用送風機の電力回生に関する研究（高ソリディティ翼による風車性能の向上）査読

織田信一, 長谷川豊, 鈴木博貴, 牛島達夫

日本機械学会論文集 81 ( 827 ) 15-00069 2015年7月

PIV計測システムの開発と格子乱流の計測

鈴木博貴, 長田孝二, 酒井康彦

可視化情報学会誌 35 ( 139 ) 29 - 34 2015年

記述言語：英語出版者・発行元：社団法人可視化情報学会

本研究は，PIV計測システムの開発と，開発したPIV計測システムを格子乱流計測に適用して検証した．本稿ではまず，研究背景およびPIV処理系の独自開発に至った動機を述べる．次に，開発した本PIV計測について，まず概要を述べたのち，解析法に重点をおいて述べる．ここでは，本PIV計測の特徴の一つである補間処理についても述べる．つづいて，本PIV計測システムを格子乱流の計測に適用した結果を，対象の流れ場と計測条件が述べられたのちに，示す．計測結果において，まず瞬時量や基本特性が示されたのち，速度変動強度の減衰が従うベキ則が示される．本計測では，このベキ則の係数を任意性なく決めるために，速度変動強度に加えて粘性散逸を用いており，これに及ぼすノイズの影響についても本稿で示される．粘性散逸を用いて算出された係数値は，先行研究の結果と良く一致し，これが一致する点において，本PIV計測システムが検証される．

DOI： 10.3154/jvs.35.139_29

DNS Study on the Development of Boundary Layer with Heat Transfer under the Effects of External and Internal Disturbances 査読

小型風車における空気密度変化に起因する運転周速比変化の定量化に関する基礎検討査読

鈴木博貴, 長谷川豊, 牛島達夫

(全文審査付) 第23回風工学シンポジウム論文集 23 103 - 108 2014年12月

自動車用送風機の電力回生に関する研究 (翼型改良による風車性能の向上）査読

織田信一, 長谷川豊, 鈴木博貴, 牛島達夫

日本機械学会論文集 80 ( 819 ) FE0315 - (11 pages) 2014年12月

Improvement of Rotor Configuration for Achievement of Automotive Fan-Turbine System 査読

Shinichi Oda, Yutaka Hasegawa, Hiroki Suzuki, Tatsuo Ushijima

(全文査読付) Proceedings of the Grand Renewable Energy 2014 International Conference and Exhibition Paper No. O-Wd-15-2 - (4 pages) 2014年7月

A 3D Navier-Stokes Simulation under Staggered/Collocated Grids with High-Kinetic-Energy-Conservation 査読

Hiroki Suzuki, Shinnosuke Matsuo, Masaya Watanabe, Yutaka Hasegawa, Tatsuo Ushijima

(全文査読付) Proceedings of the Grand Renewable Energy 2014 International Conference and Exhibition Paper No. P-Wd-2-22 - (3 pages) 2014年7月

Effects of Blade Aspect Ratio on Aerodynamic Performance of Turbine Blade in Wing-Stroke Motion 査読

Hironori Nakano, Noriyuki Tanimura, Yutaka Hasegawa, Hiroki Suzuki, Tatsuo Ushijima

(全文査読付) Proceedings of the Grand Renewable Energy 2014 International Conference and Exhibition Paper No. P-Wd-1-33 - (4 pages) 2014年7月

Study of Tower Effects on Rotor Characteristics of Horizontal Axis Wind Turbine 査読

Noriyuki Tanimura, Yutaka Hasegawa, Hiroki Suzuki, Fumiya Hara, Tatsuo Ushijima

(全文査読付) Proceedings of the Grand Renewable Energy 2014 International Conference and Exhibition Paper No. P-Wd-1-22 - (4 pages) 2014年7月

Development and Application of a Navier-Stokes Simulation Code with High- Kinetic-Energy-Conservation 査読

Hiroki Suzuki, Shinnosuke Matsuo, Yutaka Hasegawa, Tatsuo Ushijima

(全文査読付) Proceedings of the Grand Renewable Energy 2014 International Conference and Exhibition Paper No. O-Wd-1-2 - (3 pages) 2014年7月

PLIF法計測による統計分布に及ぼす時間変化/変動ノイズの影響予測（量子収率の時間変化・励起光強度・カメラゲイン変動の影響予測式と実験的検証）査読

鈴木博貴, 長田孝二, 酒井康彦, 長谷川豊, 牛島達夫

日本機械学会論文集 80 ( 813 ) FE0114 2014年5月

Development of turbulence behind the single square grid 査読

Physics of Fluids 26 ( 4 ) 045102 - (17 pages) 2014年4月

Shuang XIA, Yasumasa Ito, Koji Nagata, Yasuhiko Sakai, Hiroki Suzuki, Osamu Terashima, Toshiyuki Hayase

Journal of Fluid Science and Technology 9 ( 1 ) JFST0005 - (13 pages) 2014年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：The Japan Society of Mechanical Engineers

The effects of external and internal disturbances on the development of boundary layer with heat transfer are investigated by means of direct numerical simulation (DNS) based on the finite difference scheme. The fractional step method is used to solve the governing equations. The external disturbance is generated by a regular turbulence-generating grid, while the internal disturbance is generated by a tripping object mounted on the wall. In order to clarify the momentum and heat transfer mechanism in a boundary layer under these effects, the instantaneous and statistical characteristics of velocity and temperature fields are presented and discussed along with their interactions. The results show that the boundary layer in the case with grid turbulence becomes turbulent even though the Reynolds number based on the momentum thickness is low. On the other hand, in the case with the tripping object, only low-amplitude fluctuations are generated in the vicinity of the tripping object and the boundary layer does not fully developed. The grid increases the skin friction and enhances heat transfer more significantly than the tripping object. It is also found that strong strain in the viscous sublayer, which is induced by the vortical motion in the buffer layer, contributes to the enhancement of heat transfer.

DOI： 10.1299/jfst.2014jfst0005

直接数値計算による格子乱流の解析（不変量およびRottaモデルについて）査読

Relevance of turbulence behind the single square grid to turbulence generated by regular- and multiscale-grids 査読

Physics of Fluids 26 ( 7 ) 075105 - (22 pages) 2014年

Study on Blade Elasticity Influence on Blade Load Characteristics of NREL Turbine 査読

Fumiya Hara, Yutaka Hasegawa, Noriyuki Tanimura, Hiroki Suzuki, Tatsuo Ushijima

(全文査読付) Proceedings of the International Symposium on EcoTopia Science 2013 Paper No. 1063 - (1 page) 2013年12月

Numerical Study of Dynamic Inflow Effects on Aerodynamic Response of HAWT Rotor 査読

Yuta Taniguchi, Yutaka Hasegawa, Noriyuki Tanimura, Hiroki Suzuki, Tatsuo Ushijima

(全文査読付) Proceedings of the International Symposium on EcoTopia Science 2013 Paper No. 1034 - (1 page) 2013年12月

鈴木博貴, 長田孝二, 酒井康彦, 早瀬敏幸, 長谷川豊, 牛島達夫

日本機械学会論文集（B編） 79 ( 807 ) 2363 - 2374 2013年11月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：The Japan Society of Mechanical Engineers

The aim of this study is to address the essential features of experimental decaying grid-generated turbulence. Specifically, this study has focused on invariants of grid turbulence in the downstream region and Rotta model by means of direct numerical simulation based on the finite difference method. The mesh Reynolds number defined by the mesh size of the grid M, streamwise mean velocity and kinematic viscosity is 2; 500. Streamwise computational domain size is 112 M. The result shows that u²_oL⁴ is nearly constant such that u²_oL⁴ ∝ X^0:08 in the far downstream region, where X = x/M - x_o/M, x is the streamwise distance from the grid and x_o is the virtual origin. Rotta model is applicable in the region holding u²_oL⁴ = constant, and value of the Rotta constant is almost 1. The value can be well estimated by an estimation method introduced by previous experiments.

DOI： 10.1299/kikaib.79.2363

Analysis of Flow Characteristics of Turbulent Plane Jets Based on Velocity and Scalar Fields Using DNS 査読

DNS of Channel Flow with Two-Scale Surface Roughness on One Wall 査読

Hiroki Suzuki, Richard J. Perkins

(全文査読付) Proceedings of the 14th European Turbulence Conference Paper No. 115 - (2 pages) 2013年9月

Study on the Effects of Grid-Generated Turbulence on the Initial Growth of Turbulent Boundary Layer by Direct Numerical Simulation 査読

S. Xia, Y. Ito, K. Nagata, Y. Sakai, H. Suzuki, O. Terashima, T. Hayase

(全文査読付) Proceedings of the 4th International Conference on Jets, Wakes and Separated Flows paper No. 1169 - (4 pages) 2013年9月

Direct Numerical Simulation of Single-Square Grid-Generated Turbulence 査読

Y. Zhou, K. Nagata, Y. Sakai, H. Suzuki, Y. Ito, O. Terashima, T. Hayase

(全文査読付) Proceedings of the 4th International Conference on Jets, Wakes and Separated Flows paper No. 1102 - (5 pages) 2013年9月

Effects of Initial Condition on Coherent Structure and Evolution of Turbulent Plane Jets 査読

N. Wu, Y. Sakai, K. Nagata, H. Suzuki, O. Terashima, T. Hayase

(全文査読付) Proceedings of the 4th International Conference on Jets, Wakes and Separated Flows paper No. 1010 - (6 pages) 2013年9月

Measurement of Axial Turbulent Scalar Flux of High Sc/Low Re Round Jet Using Line Scan Camera 査読

Hiroshi Nishiyama, Tatsuo Ushijima, Hiroki Suzuki, Yutaka Hasegawa

(全文査読付) Proceedings of the 4th International Conference on Jets, Wakes and Separated Flows Paper No. 1193 - (5 pages) 2013年9月

Development and Quantitative Validation of a Numerical Code Using Highly Energy-Conservative Scheme 査読

Masaya Watanabe, Hiroki Suzuki, Yutaka Hasegawa, Tatsuo Ushijima

(全文査読付) Proceedings of the 4th International Conference on Jets, Wakes and Separated Flows Paper No. 1170 - (4 pages) 2013年9月

DNS Study on Pressure Characteristics of Fractal- Generated Turbulence 査読

Hiroki Suzuki, Kouji Nagata, Yasuhiko Sakai, Toshiyuki Hayase, Yutaka Hasegawa, Tatsuo Ushijima

(全文査読付) Proceedings of the 4th International Conference on Jets, Wakes and Separated Flows Paper No. 1109 - (4 pages) 2013年9月

DNS on Multiscale- Generated Grid Turbulence Using Classical Grid 査読

Hiroki Suzuki, Kouji Nagata, Yasuhiko Sakai, Toshiyuki Hayase, Yutaka Hasegawa, Tatsuo Ushijima

(全文査読付) Proceedings of the 8th International Symposium on Turbulence and Shear Flow Phenomena Paper No. HOM1E - (6 pages) 2013年8月

Nannan Wu, Yasuhiko Sakai, Kouji Nagata, Hiroki Suzuki, Osamu Terashima, Toshiyuki Hayase

Journal of Fluid Science and Technology 8 ( 3 ) 247 - 261 2013年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：The Japan Society of Mechanical Engineers

Turbulent plane jets are prototypical free shear flows on which fundamental research can expand the overall understanding of turbulent flows. In this study, flow characteristics of the turbulent plane jets are studied by means of direct numerical simulation (DNS) based on the finite difference method. The effects of the initial conditions at the jet exit (i.e. Reynolds number and velocity profile) on the spatial development of velocity and scalar fields are mainly investigated. Meanwhile the instantaneous coherent structures, based on the Q-criterion and the local minimum of pressure, are presented. The results suggest that the plane jet flow with the higher Re (=U_bd/ν : U_b is the bulk mean velocity at the jet exit, d is the slot width, and ν is the kinematic viscosity) and the parabola velocity profile at the jet exit will correspond to the shorter potential core, furthermore, the lower Re and the parabola velocity profile will strengthen the decay of the mean field in the process of flow transition to full turbulence. The flow self-similarity will be achieved at shorter streamwise distance from the jet exit for the higher Re and the parabola velocity profile at the jet exit. Moreover, the dependency of coherent structures on the initial Reynolds number is remarkable, especially in the flow development region, but the change of initial velocity profile at the jet exit hardly acts on the scale of coherent structures. It is also observed that the scalar field is more sensitive to changes of initial conditions than the velocity field.

DOI： 10.1299/jfst.8.247

フラクタル格子乱流の空間発展に関する風洞実験（第2報，I型及びX型熱線プローブを用いた乱流場の乱れエネルギ輸送の計測）査読

Fractal analysis of turbulent mixing in fractal-generated turbulence by planar laser-induced fluorescence 査読

Hiroki Suzuki, Kouji Nagata, Yasuhiko Sakai, Yutaka Hasegawa

Physica Scripta 88 ( 155 ) 014062 - (5 pages) 2013年7月

An Attempt to Improve Accuracy of PIV Using an Interpolation Method 査読

Hiroki Suzuki, Tatsuo Ushijima, Yutaka Hasegawa, Kouji Nagata, Yasuhiko Sakai

(全文査読付) Proceedings of the 12th Asian Symposium on Visualization Paper No.218 - (4 pages) 2013年5月

Visualization of turbulent reactive jet by using direct numerical simulation 査読

Tomoaki Watanabe, Yasuhiko Sakai, Kouji Nagata, Osamu Terashima, Hiroki Suzuki, Toshiyuki Hayase, Yasumasa Ito

International Journal of Modeling, Simulation, and Scientific Computing 4 ( SUPPL.1 ) 1341001 - (16 pages) 2013年

稲葉拓人, 長田孝二, 酒井康彦, 鈴木浩之, 寺島修, 鈴木博貴

日本機械学会論文集 B編 79 ( 804 ) 1476 - 1488 2013年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人日本機械学会

Spatial development of a turbulent field generated by a multiscale, fractal-grid is investigated in a wind tunnel. A square type (i.e., fractal elements with square shapes) fractal grid is placed at the inlet of the test section. The Reynolds number based on the length of the biggest grid bar is set to 5900. The spatial developments of cross-sectional profiles of turbulent kinetic energy K, dissipation rate of K, ε, and the advection, production, triple-correlation transport, pressure transport and viscous diffusion terms in the transport equation of K are measured by using a hot wire anemometer. The results show that in the upstream region, turbulence produced by the biggest grid bar is transported to the central and outward regions by the triple-correlation term T. In the decay region, there is low turbulence production downstream of the interior of the biggest grid bar, which is mainly transported outward rather than to the central region by T. The advection term is large and positive in the decay region whereas the pressure transport and the viscous diffusion terms are very small in the decay region.

DOI： 10.1299/kikaib.79.1476

フラクタル格子乱流の空間発展に関する風洞実験（第1報，I型熱線プローブを用いた乱流場の基本特性の計測）査読

鈴木浩之, 長田孝二, 酒井康彦, 鈴木博貴, 寺島修, 稲葉拓人

日本機械学会論文集 B編 79 ( 798 ) 115 - 125 2013年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人日本機械学会

Spatial development of a turbulent field generated by a multiscale, fractal-grid is investigated in a wind tunnel. A square type (i.e., fractal elements with square shapes) fractal grid is placed at the inlet of the test section. The Reynolds numbers based on the length of the biggest grid bar are set to 5900 and 11400. Turbulent characteristics in the downstream region of the grid are measured by using a hot wire anemometer. The results on the centerline statistics are compared with those in the previous experiments at the same Reynolds numbers. The results on the centerline statistics generally agree with the previous measurements despite the difference in the size of the test sections used. The spatial developments of cross-sectional profiles are also measured. It is found that the non-uniformity in the mean velocity field almost disappear in the downstream direction, although the non-uniformities of higher-order statistics are still observed even in the far downstream region. In the entire cross section of the tunnel, the ratio of the integral length scale L_u to the Taylor microscale λ hardly changes in the decay region of the rms velocity. These results will provide useful information in clarifying the non Richardson-Kolmogorov cascade process in the fractal-generated turbulence found in the previous measurement (Mazellier and Vassilicos, Physics of Fluids, Vol. 22, 075101 2010).

DOI： 10.1299/kikaib.79.115

正方格子およびフラクタル格子乱流場における高シュミット数スカラ混合に関する実験的研究査読

Turbulence structure and turbulence kinetic energy transport in multiscale/fractal-generated turbulence 査読

Kouji Nagata, Yasuhiko Sakai, Takuto Inaba, Hiroki Suzuki, Osamu Terashima, Hiroyuki Suzuki

Physics of Fluids 25 ( 6 ) 065102 - (26 pages) 2013年

星野晃一, 長田孝二, 酒井康彦, 鈴木博貴, 鵜飼涼太, 寺島修, 伊藤靖仁

日本機械学会論文集 B編 79 ( 799 ) 304 - 316 2013年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人日本機械学会

High-Schmidt-number scalar mixing layers in a turbulent flow generated by regular and fractal grids are investigated by means of experiments using particle image velocimetry (PIV) and planar laser induced fluorescence (PLIF) technique. The Reynolds number based on the mesh size is 2,500. Rhodamine B is used as a fluorescent dye. The Schmidt number is about 2,100. The flow is separated into upper and lower layers by a splitter plate installed upstream of the grids; thus, the turbulent scalar mixing layers develop downstream of the grids. The results show that fractal grid turbulence has stronger turbulence intensity than that in regular grid turbulence. The decay exponent of turbulence intensity, n, is n = 1.21 for the regular grid and n = 1.40 for the fractal grid. The eddy diffusivity for mass in fractal grid turbulence is approximately four times larger than that in regular grid turbulence. The scalar dissipation in fractal grid turbulence is smaller than that in regular grid turbulence. Finally, it is concluded that turbulent scalar mixing is more enhanced by the fractal grid than by the regular grid.

DOI： 10.1299/kikaib.79.304

乱流境界層の統計的特性に及ぼす円柱後流による主流乱れの影響査読

晝田紘佑, 長田孝二, 酒井康彦, 鈴木博貴, 寺島修

日本機械学会論文集 B編 79 ( 799 ) 291 - 303 2013年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人日本機械学会

Effects of the cylinder wake in a freestream on statistical properties of a turbulent boundary layer over a flat plate are investigated by means of wind tunnel experiments. The cylinder is set horizontally over the flat plate and the interactions between its wake and the zero-pressure-gradient turbulent boundary layer are investigated. Instantaneous velocity is measured by using hot wire anemometry. The bursting events are detected by the variable interval time average (VITA) technique. The results show that the time-averaged mean velocity in the inner layer with the cylinder wake coincides with that without the cylinder wake. However, turbulence intensities normalized by the inner parameters are suppressed by the cylinder wake. It is found that the peak value of the velocity fluctuation during the sweep phase in the bursting event is increased by the cylinder wake.

DOI： 10.1299/kikaib.79.291

Investigation of Eddy Diffusivity in a Reactive Plane Jet by using Direct Numerical Simulation 査読

Quantitative visualization of high-Schmidt-number turbulent mixing in grid turbulence by means of PLIF 査読

Hiroki Suzuki, Kouji Nagata, Yasuhiko Sakai

Journal of Visualization 15 ( 2 ) 109 - 117 2012年5月

Tomoaki Watanabe, Yasuhiko Sakai, Kouji Nagata, Osamu Terashima, Yasumasa Ito, Hiroki Suzuki, Toshiyuki Hayase

(全文査読付) Communications in Computer and Information Science 323 CCIS ( PART 1 ) 144 - 150 2012年

輝度分布補間によるPIV計測精度向上（擬似粒子画像によるフーリエ補間の導入効果の解析）査読

鈴木博貴, 長田孝二, 酒井康彦, 長谷川豊

日本機械学会論文集（B編） 78 ( 790 ) 1248 - 1259 2012年

Quantitative Visualization of High-Schmidt-Number Scalar Mixing in Grid Turbulence 査読

Hiroki Suzuki, Kouji Nagata, Yasuhiko Sakai

(全文査読付) Proceedings of the 11th Asian Symposium on Visualization Paper No. ASV11-04-05 - (8 pages) 2011年6月

An experimental study on turbulent mixing of high-Schmidt-number scalar in grid turbulence by means of PIV and PLIF 査読

Hiroki Suzuki, Kouji Nagata, Yasuhiko Sakai, Ryota Ukai

ASME-JSME-KSME 2011 Joint Fluids Engineering Conference, AJK 2011 1 ( D ) 3763 - 3767 2011年

DNS on a spatially developing grid turbulence 査読

Hiroki Suzuki, Kouji Nagata, Yasuhiko Sakai, Toshiyuki Hayase

(全文査読付) Proceedings of the 13th European Turbulence Conference 318 032043 - (5 pages) 2011年

格子乱流の影響を受けた乱流境界層の統計的特性（直接数値計算による空間発展解析）査読

鈴木博貴, 長田孝二, 酒井康彦, 早瀬敏幸

日本機械学会論文集（B 編） 77 ( 775 ) 737 - 748 2011年

Direct Numerical Simulation on Turbulence Structures in a Transition Process of a Spatially Developing Turbulent Plane Jet 査読

Hiroki Suzuki, Yasuhiko Sakai, Kouji Nagata, Daisuke Sugimoto

(全文査読付) Proceedings of the 3rd International Conference on Jets, Wakes, and Separated Flows CD-ROM - (6 pages) 2010年9月

Direct Numerical Simulation of Regular and Fractal-Grid Turbulence Using the Immersed Boundary Method and Fully Conservative Higher Order Finite-Difference Schemes 査読

Hiroki Suzuki, Kouji Nagata, Yasuhiko Sakai, Toshiyuki Hayase

International Review of Physics 4 ( 2 ) 83 - 90 2010年4月

S0502-7-4 外部乱れの影響を受けた乱流境界層の統計的特性について([S0502-7]噴流,後流および剥離流れ現象の解明と制御(7))

佃紗織, 鈴木博貴, 北山智之, 長田孝二, 酒井康彦

年次大会講演論文集 2010 217 - 218 2010年

記述言語：日本語出版者・発行元：一般社団法人日本機械学会

The effects of free-steam turbulence on a turbulent boundary layer are experimentally investigated by using a wind tunnel. For the case with free stream turbulence, turbulence-generating grid is placed upstream of the leading end of a flat plate, on which turbulent boundary layer is developed. The Reynolds number based on the momentum thickness is Re_θ=2990 for the case with and without grid turbulence. Instantaneous streamwise velocity is measured using a hot-wire anemometry with an inhouse I-type probe. The effects of free-stream turbulence on statistical properties of the turbulent boundary layer are discussed.

DOI： 10.1299/jsmemecjo.2010.2.0_217

S0502-7-3 高精度PLIFによる高Sc数スカラー乱流混合の実験解析([S0502-7]噴流,後流および剥離流れ現象の解明と制御(7))

鵜飼涼太, 鈴木博貴, 長田孝二, 酒井康彦

年次大会講演論文集 2010 215 - 216 2010年

記述言語：日本語出版者・発行元：一般社団法人日本機械学会

High-Schmidt-number scalar mixing layers in the grid turbulence are experimentally investigated in a water channel by means of the planar laser induced fluorescence (PLIF) technique and the time-resolved particle image velocimetry (PIV). A biplane square grid and a fractal square grid are used to generate turbulence. The Reynolds number based on the effective mesh size and mean velocity is 2,500 in both flows. Fluorescent dye (Rhodamine B; Schmidt number is about 2,100) is homogeneously premixed only in the upper stream, and therefore, the scalar mixing layer with an initial step profile develops downstream of the grid. Various turbulence quantities are evaluated and comparisons are made between turbulence and scalar fields generated by the regular and fractal grids.

DOI： 10.1299/jsmemecjo.2010.2.0_215

S0502-1-1 DNSによる二次元乱流噴流の空間構造に関する研究([S0502-1]噴流,後流および剥離流れ現象の解明と制御(1))

杉本大輔, 鈴木博貴, 酒井康彦, 長田孝二

年次大会講演論文集 2010 143 - 144 2010年

記述言語：日本語出版者・発行元：一般社団法人日本機械学会

Spatial structures of a turbulent plane jet are investigated by the direct numerical simulation (DNS) based on the finite difference method. Reynolds number is 1500. Special care has been paid to the boundary condition to reproduce proper entrainments. In this study, we focused on the pressure fluctuations, velocity gradient tensors, and rate-of-rotation tensors in the transition region of the jet, which are difficult to measure.

DOI： 10.1299/jsmemecjo.2010.2.0_143

埋め込み境界法と高精度差分によるフラクタル格子乱流の三次元直接数値計算査読

Direct numerical simulation of turbulent mixing in regular and fractal grid turbulence 査読

Hiroki Suzuki, Kouji Nagata, Yasuhiko Sakai, Toshiyuki Hayase

Physica Scripta T T142 2010年

フラクタル格子により生成されるマルチスケール誘起乱流の構造とスカラー拡散機構（第２報，DNS による一様等方性と間欠性に及ぼす格子パラメータの影響の検討）査読

鈴木博貴, 長田孝二, 酒井康彦, 早瀬敏幸

日本機械学会論文集（B編） 76 ( 772 ) 2024 - 2031 2010年

高Sc数スカラー乱流輸送に対するPLIF計測の補正処理法（励起光強度の時空間変化および量子収率の時間変化の非計測補正）査読

鈴木博貴, 長田孝二, 酒井康彦, 鵜飼涼太

日本機械学会論文集（B編） 76 ( 770 ) 1543 - 1551 2010年

鈴木博貴, 長田孝二, 酒井康彦, 早瀬敏幸

数理科学会論文集 11 ( 1 ) 33 - 38 2009年12月

フラクタル格子により生成されるマルチスケール誘起乱流の構造とスカラー拡散機構（第１報，DNS によるフラクタル基本形状の影響に関する検討）査読

鈴木博貴, 長田孝二, 酒井康彦, 早瀬敏幸, 久保貴

日本機械学会論文集（B編） 75 ( 755 ) 1387 - 1394 2009年7月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人日本機械学会

Turbulence characteristics in the spatially developing fractal-generated turbulence are investigated by means of the direct numerical simulation (DNS). Three kinds of fractal grids, namely, cross, I and square types, are numerically constructed using the immersed boundary method. The results show that fractal grids generate high turbulence intensities compared with the classical grid turbulence using a biplane square mesh grid at the same mesh Reynolds number. Among the three types, the fractal square grid is the best to generate nearly homogeneous and isotropic turbulence in the far downstream decaying region. The integral length scale in the fractal generated turbulence remains approximately constant in the decaying region, whereas it grows downstream in the classical grid turbulence. These results are in good agreement with the previous experiments.

DOI： 10.1299/kikaib.75.755_1387