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Effect of Non-Newtonian Viscosity for Surfactant Solutions on Vortex Characteristics in a Swirling Pipe Flow

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Journal of Thermal Science 2005年第4期14卷 357-361,356页

作者： Mizue MUNEKATA hidefumi TAKAKI hideki ohba Kazuyoshi MATSUZAKI Kumamoto University 2-39-1 KurokamiKumamoto 860-8555Japan Tokyo Electron LTD. 650 Mitsuzawa Hosaka-cho NirasakiYamanashi 407-0192Japan

Effects of non-Newtonian viscosity for surfactant solution on the vortex characteristics and drag-reducing rate in a swirling pipe flow are investigated by pressure drop measurements, velocity profile measurements and viscosity measurements. Non-Newtonian viscosity is represented by power-law model （t= kD^π）. Surfactant solution used has shear-thinning viscosity with n 〈 1.0. The swirling flow in this study has decay of swirl and vortex-type change from Rankin＇s combined vortex to forced vortex. It is shown that the effect of shear-thinning viscosity on the decay of swirl intensity is different by vortex category and the critical swirl number with the vortex-type change depends on shear-thinning viscosity.

关键词： swirling flow drag reduction surfactant solution non-Newtonian fluid vortex LDV.

An Experimental Study on Aerodynamic Sound Generated from Wake Interaction of Circular Cylinder and Airfoil with Attack Angle in Tandem

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Journal of Thermal Science 2008年第3期17卷 212-217页

作者： Mizue MUNEKATA Ryuta KOShiIShi hiroyuki YOShiKAWA hideki ohba Department of Mechanical System Engineering

In our previous study, the effects of the interval between the cylinder and the airfoil on the aerodynamic sound were investigated and compared with the cases of single circular and single airfoil. In this study, the effects of the attack angle of the airfoil located downstream on the characteristics of aerodynamic sound and the wake structure are investigated at a given interval between the cylinder and the airfoil. It is found that the sound pressure level of DFN and the peak frequency decrease with increasing attack angle of airfoil because of the diffusive wake structure due to the increased back pressure of circular cylinder, which is caused by the blocking effect of airfoil. It is shown that the sound sources are corresponded to the attack points of shedding vortex form the upstream circular cylinder to the downstream airfoil. We conclude that the pressure fluctuation at the airfoil surface effects on the sound pressure level, from the flow visualizations and the exploration test of sound source.

关键词： aerodynamic sound wake interaction circular cylinder airfoil Karman's vortex flow visualization

Carbonation of low heat portland cement paste precured in water for different time

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Journal of University of Science and Technology Beijing 2007年第2期14卷 178-184页

作者： Deping Chen Etsuo Sakai Masaki Daimon Yoko ohba Civil and Environmental Engineering School University of Science and Technology Beijing Beijing 100083 China Graduate School of Science and Engineering Tokyo Institute of Technology Tokyo 152-8552 Japan

The carbonation technique was applied to accelerate the hydration of low heat portland cement （LHC）. Before carbonation, the demoulded pastes were precured in water for 0, 2, 7, and 21 d, respectively. The results show that precuring time in water strongly influences the carbonation process. The phenolphthalein test indicates that the paste precured in water for a shorter time is more quickly carbonated than that for a longer time. The content of calcium hydroxide increases with increasing the precuring time in water, whereas, the amount of absorbed carbon dioxide changes contrarily. Scanning electron microscope （SEM） observation shows that portlandite always fills up big air bubbles in the paste during precuring in water, and the mercury intrusion porosimetry （MIP） results show that there are less large capillary pores in the paste precured in water for a longer time. It is found that the paste without precuring in water has more carbon dioxide absorption during curing in carbon dioxide atmosphere, and its total pore volume decreases remarkably with an increase in the carbonation time than that precured in water. X-ray diffraction （XRD） and Brunauer-Emmett-Teller （BET） surface area analyses indicate that the carbonate products are vaterite and calcite; CxSHy formed from carbonation has low BET surface area in comparison with that of C-S-H formed from curing in water.

关键词： carbonation carbon dioxide absorption vaterite BET surface area pore size distribution

Effects of Pulsation on Separated Flow and Heat Transfer in Enlarged Channel

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Journal of Thermal Science 2011年第1期20卷 70-75页

作者： hiroyuki YOShiKAWA Tomonori KAI Mizue MUNEKATA hideki ohba Dept.of Mechanical System Engineering Kumamoto University2-39-1 KurokamiKumamoto 860-8555Japan Graduate School of Science and Technology Kumamoto University2-39-1 KurokamiKumamoto 860-8555Japan Kikuyo KikuchiKumamoto 869-1101Japan

Numerical results of three-dimensional separated flow and heat transfer in an enlarged rectangular channel are presented in this *** expansion ratio and aspect ratio of the channel are 2.0 and 16.0,*** number of the flow is 200 and it is over the critical Reynolds *** the critical Reynolds number,the flow in the symmetric channel becomes asymmetric and deflects to one side of the *** of the pulsating fluctuation at the inlet upon the flow in the channel are *** is clarified that the inlet flow with a pulsating fluctuation of Strouhal number 0.05 and 0.10 strongly affects on the flow in the channel,and heat transfer on the walls is enhanced,especially on the wall surface covered with long separation *** the other hand,the pulsation of St=0.0125 oscillates the shear layer more weakly than that of St=0.05,0.10 and the enhancement of heat transfer is smaller,though some vortices are shed from the vicinity of the side wall near the reattachment *** oscillation of the main flow calms down gradually as the Strouhal number of the pulsation increases over *** influence of pulsation of St=0.20 on the flow is restricted in the near downstream of the step,and heat transfer on the walls is almost similar to that of the steady flow in the channel.

关键词： Pulsating Fluctuation Symmetric Enlarged Channel Separated Flow Heat Transfer

Creation of crystal structure reproducing X-ray diffraction pattern without using database

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npj Computational Materials 2023年第1期9卷 946-954页

作者： Joohwi Lee Junpei Oba Nobuko ohba Seiji Kajita Toyota Central R&D Labs. Inc.41-1 YokomichiNagakuteAichi 480-1192Japan

When a sample’s X-ray diffraction pattern(XRD)is measured,the corresponding crystal structure is usually determined by searching for similar XRD patterns in the ***,if a similar XRD pattern is not found,it is tremendously laborious to identify the crystal structure even for *** case commonly happens when researchers develop novel and complex *** this study,we propose a crystal structure creation scheme that reproduces a given XRD *** employed a combinatorial inverse design method using an evolutionary algorithm and crystal morphing(Evolv&Morph)supported by Bayesian optimization,which maximizes the similarity of the XRD patterns between target one and those of the created crystal *** sixteen different crystal structure systems with twelve simulated and four powder target XRD patterns,Evolv&Morph successfully created crystal structures with the same XRD pattern as the target(cosine similarity 99%for the simulated ones and>96%the experimentally measured ones).Furthermore,the present method has merits in that it is an automated crystal structure creation scheme,not dependent on a *** believe that Evolv&Morph can be applied not only to determine crystal structures but also to design materials for specific properties.

关键词： properties crystal structure

Numerical Study on Particle Motions in Swirling Flows in a Cyclone Separator

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Journal of Thermal Science 2006年第2期15卷 181-185页

作者： Kazuyoshi MATSUZAKI hideaki UShiJIMA Mizue MUNEKATA hideki ohba Tokyo Electron LTD. 650 Mitsuzawa Hosaka-cho Nirasaki Yamanashi 407-0192 Japan Kumamoto University 2-39-1 Kurokami Kumamoto 860-8555 Japan

The purpose of this study is to establish the high-accurate prediction method of particle separation in a cyclone separator. Numerical simulation of the swirling flows in a cyclone separator is performed by using a large eddy simulation （LES） based on a Smagorinsky model. The validity of the simulation and the complicated flow characteristics are discussed by comparison with experimental results. Moreover, particle motions are treated by a Lagrangian method and are calculated with a one-way method. A performance for particle separation is predicted from the results of the particle tracing. As results of our investigation, the influences of the inserted height of the outlet pipe on the performance for particle separation of cyclone separator are shown.

关键词： cyclone separator swirling flow particle motion large eddy simulation

Tracking people through partial occlusions

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The Journal of China Universities of Posts and Telecommunications 2009年第2期16卷 117-121页

作者： LU Jian-guo CAI An-hi School of Information and Communication Engineering Beijing University of Posts and Telecommunications Beijing 100876 China

This article presents a novel people-tracking approach to cope with partial occlusions caused by scene objects. Instead of predicting when and where the occlusions will occur, a part-based model is used to model the pixel distribution of the target body under occlusion. The subdivided patches corresponding to a template image will be tracked independently using Markov chain Monte Carlo （MCMC） method. A set of voting-based rules is established for the patch-tracking result to verify if the target is indeed located at the estimated position. Experiments show the effectiveness of the proposed method.

关键词： partial occlusion part-based model MCMC voting-based rules

Influences of the Exhaust Flow on the Boundary Layer Flow on the Wafer Surface in Spin Coating System

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Journal of Thermal Science 2005年第2期14卷 130-135页

作者： Seiichi KIMURA Mizue MUNEKATA hiroaki KURIShiMA Kazuyoshi MATSUZAKI hideki ohba Graduate School of Science and Technology Kumamoto University Mechanical Engineering and Materials Science Kumamoto UniversityTokyo Electron Kyushu LTDTokyo Electron AT LTDMechanical Engineering and Materials Science Kumamoto University

Recently, development of high technology has been required for the formation of thin uniform film in manufacturing processes of semiconductor as the semiconductor become more sophisticated. Spin coating is usually used for spreading photoresist on a wafer surface. However, since rotating speed of the disk is very high in spin coating, the dropped resist scatters outward and reattaches to the film surface. So, the scattered resist is removed by the exhaust flow generated at the gap between the wafer edge and the catch cup. It is seriously concerned that the stripes called Ekman spiral vortices appears on the disk in the case of high rotating speed and the film thickness increases near the wafer edge in the case of low rotating speed, because it prevent the formation of uniform film. The purpose of this study is to make clear the generation mechanism of Ekman spiral vortices and the influence of exhaust flow on it Moreover the influence of the catch cup geometry on the wafer surface boundary layer flow is investigated.

关键词： rotating disk flow spin coating boundary layer flow hot-wire measurement

Relation between the Three-dimensional Flow Structure and Aerodynamic Sound Generated from Inclined Circular Cylinder

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Journal of Thermal Science 2004年第2期13卷 127-132页

作者： Mitsuru ShiNGAI Yasutake HARAMOTO Kazuyoshi MATSUZAKI Mizue MUNEKATA hideki ohba Dept. of Mechanical Engineering and Materials Science Kumamoto University Kurokami 2-39-1 Kumamoto 860-8555 Japan Mitsui Miike Machinery Co. LTD Asahi-machi 2-28 Ohmuta Fukuoka 836-8588 Japan

The major causes of the sound pressure level (SPL) variation due to the changes of the inclined angle of a circular cylinder and the aspect ratio (ratio of distance between endplates to cylinder diameter) were investigated. The velocity fluctuation of the wake and the surface pressure fluctuation of the cylinder were measured in a low noise wind tunnel to find the correlation length, coherent output power and Strouhal number. The results show that the changes of these values qualitatively correspond with the change of SPL. Flow visualization tests are performed to clarify the variation of wake in relation with inclined angle and aspect ratio. It is found that the spanwise structure of Karman’s vortex street is broken down by the upward flows generated around the bottom endplate, and the degree of the interference between the upward flow and Karman’s vortex street is smaller when the aspect ratio is larger.

关键词： aerodynamic sound correlation length coherent output power Strouhal number flow visualization.