Faculty Profiles - Suzuki Hiroki

Papers - Suzuki Hiroki

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

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

Proceedings of the 4th International Conference on Jets, Wakes and Separated Flows paper No. 1169 - (4 pages) 2013.9

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

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

Proceedings of the 4th International Conference on Jets, Wakes and Separated Flows paper No. 1102 - (5 pages) 2013.9

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

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

Proceedings of the 4th International Conference on Jets, Wakes and Separated Flows paper No. 1010 - (6 pages) 2013.9

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

Hiroshi Nishiyama, Tatsuo Ushijima, Hiroki Suzuki, Yutaka Hasegawa

Proceedings of the 4th International Conference on Jets, Wakes and Separated Flows Paper No. 1193 - (5 pages) 2013.9

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

Masaya Watanabe, Hiroki Suzuki, Yutaka Hasegawa, Tatsuo Ushijima

Proceedings of the 4th International Conference on Jets, Wakes and Separated Flows Paper No. 1170 - (4 pages) 2013.9

DNS Study on Pressure Characteristics of Fractal- Generated Turbulence Reviewed

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

Proceedings of the 4th International Conference on Jets, Wakes and Separated Flows Paper No. 1109 - (4 pages) 2013.9

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

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

Journal of Fluid Science and Technology 8 ( 3 ) 247 - 261 2013.8

Language：English Publishing type：Research paper (scientific journal) Publisher：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

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DNS on Multiscale- Generated Grid Turbulence Using Classical Grid Reviewed

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

Proceedings of the 8th International Symposium on Turbulence and Shear Flow Phenomena Paper No. HOM1E - (6 pages) 2013.8

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

Hiroki Suzuki, Kouji Nagata, Yasuhiko Sakai, Yutaka Hasegawa

Physica Scripta 88 ( 155 ) 014062 - (5 pages) 2013.7

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

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

Proceedings of the 12th Asian Symposium on Visualization Paper No.218 - (4 pages) 2013.5

Visualization of turbulent reactive jet by using direct numerical simulation Reviewed

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

Wind Tunnel Experiments on the Spatial Development of Fractal-Grid Turbulence (2nd Report, Measurements of Turbulent Kinetic Energy Transport by Using I- and X-Type Hot-Wire Probes) Reviewed

INABA Takuto, NAGATA Kouji, SAKAI Yasuhiko, SUZUKI Hiroyuki, TERASHIMA Osamu, SUZUKI Hiroki

Transaction of the Japan Society of Mechanical Engineering Series B 79 ( 804 ) 1476 - 1488 2013

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Mechanical Engineers

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

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Wind Tunnel Experiments on the Spatial Development of Fractal-Grid Turbulence (1st Report, Measurements of Fundamental Turbulence Properties by Using an I-Type Hot-Wire Probe) Reviewed

NAGATA Kouji, TERASHIMA Osamu

Transaction of the Japan Society of Mechanical Engineering Series B 79 ( 798 ) 115 - 125 2013

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Mechanical Engineers

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

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

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

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

Experimental Study on the Mixing of High-Schmidt-Number Scalar in Regular/Fractal Grid Turbulence Reviewed

NAGATA Kouji, TERASHIMA Osamu, ITO Yasumasa

Transaction of the Japan Society of Mechanical Engineering Series B 79 ( 799 ) 304 - 316 2013

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Mechanical Engineers

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

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Effects of the Cylinder Wake in a Freestream on Statistical Properties of a Turbulent Boundary Layer Reviewed

NAGATA Kouji, TERASHIMA Osamu

Transaction of the Japan Society of Mechanical Engineering Series B 79 ( 799 ) 291 - 303 2013

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Mechanical Engineers

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

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

Hiroki Suzuki, Kouji Nagata, Yasuhiko Sakai

Journal of Visualization 15 ( 2 ) 109 - 117 2012.5

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

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

Communications in Computer and Information Science 323 CCIS ( PART 1 ) 144 - 150 2012

Improved PIV analysis using an interpolation technique (analysis on improvement effects of the fourier interpolation using quasi particle-images) Reviewed

Hiroki Suzukib, Kouji Nagata, Yasuhiko Sakai, Yutaka Hasegawa

Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B 78 ( 790 ) 1248 - 1259 2012

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

Hiroki Suzuki, Kouji Nagata, Yasuhiko Sakai

Proceedings of the 11th Asian Symposium on Visualization Paper No. ASV11-04-05 - (8 pages) 2011.6

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Papers - Suzuki Hiroki