Papers - Sawada, Tatsuo

Sloshing motion of a magnetic fluid in a cylindrical container due to horizontal oscillation

Tatsuo Sawada, Yasuhiro Ohira and Hiroshi Houda

Energy Conversion and Management (Pergamon)  43 ( 3 ) 299-308 2002.01

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0196-8904

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Sloshing is a phenomenon that occurs when a liquid with a free surface is severely agitated in a liquid storage container. In an axisymmetric container, even though the excitation is lateral, the liquid oscillates with rotational movement around the central axis of the container. This phenomenon is called swirling and may be unstable swirling or stable swirling. We measure the velocity profile of a sloshing magnetic fluid using an ultrasonic Doppler velocimetry method called UVP, and examine the relationship between internal velocity profiles and swirling phenomena, in particular, stable swirling phenomena. We calculated power spectra from the velocity data using a fast Fourier transform and observed that the most dominant peak in the power spectrum moved to higher frequencies as the magnetic field intensity was increased, whereas a derived peak at a lower frequency moved to lower frequencies as the magnetic field intensity was increased.

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elocity Profile Measurement on Oscillating Pipe Flow of a Magnetic Fluid by UVP Method

Gentaro Yamanaka, Hiroshige Kikura, Yasushi Takeda, Tatsuo Sawada and Masanori Aritomi

Transaction of The Japan Society of Mechanical Engineers, Ser.B (The Japan Society of Mechanical Engineers)  67 ( 663 ) 2717-2724 2001.11

Research paper (scientific journal), Joint Work, Accepted

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This paper presents velocity profile measurements of an oscillatory pipe flow of magnetic fluid by Ultrasonic Velocity Profile (UVP) method. Experiments are performed at Reynols number Rc=367, defined by mean velocity amplitude and a pipe diameter, and non dimensional angular frequency W=4.76. It is shown that velocity amplitude increases in the center of a pipe and decreases in the near wall region under non-uniform magnetic field. The comparison of measured data under non magnetic field with those obtained from the theory of Newtonian-fluid reveals that noticeable discrepancies exist between them.

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Large-amplitude axisymmetric mode oscillations of a magnetic fluid column supported by a magnetic field

Motoyoshi Ohaba, Yuko Suzuki, Masaaki Takeuchi, Tatsuo Sawada, Seiichi Sudo, Takahiko Tanahashi

Journal of the Japan Society of Microgravity Application (Japan Society of Microgravity Application)  18 ( 4 ) 269-275 2001.10

Research paper (scientific journal), Joint Work, Accepted

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Axisymmetric mode oscillations of a magnetic fluid column supported by a magnetic field are examined experimentally in the presence of gravity. A magnetic fluid column, height 9.78 mm, is formed vertically in a magnetic field generated by Helmholtz like coils fastened on an electrodynamic exciter, and vibrated vertically to produce axisymmetric oscillations. Nonlinear jumping phenomena, transition from the (0, 1) mode standing wave to the progressive wave and mode coupling are observed at larger amplitude oscillations. One-half subharmonic oscillations such as the (3, 1), (4, 1) and (5, 1) modes arise beyond some threshold values of the excitation amplitude. These new phenomena are useful to discuss the liquid column oscillations in a microgravity environment in the Floating Zone Technique.

Visualization of natural convection of different unmixed liquids in a cubic container

Saiguang Wang, Tatsuo Sawada, Takahiko Tanahashi

Transactions of the Visualization Society of Japan (Visualization Society of Japan)  21 ( 1 ) 6-11 2001.01

Research paper (scientific journal), Joint Work, Accepted,  ISSN  1346-5252

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Natural thermal convection of different unmixed liquids is quite different from that of a single liquid because of the existence of liquid-liquid interface. In order to clarify this phenomenon, it is necessary to know both flow and temperature fields of different unmixed liquids. In the present paper, natural convection of different unmixed liquids in a cubic enclosure with isothermal hot and cold walls was investigated. Influence of difference of kinematic viscosities and volume ratio of two liquids on flow and temperature fields were experimentally studied. Temperature distribution on a central cross section was visualized by thermosensitive liquid crystal particles. The conclusions derived from the above experiment are as follows: As the thermal movement occur through the interface, The reverse speed of two kind of liquids near the interface was promoted. And beside the main circulation that occurred in the liquids of higher volume ratio and lower viscosity ratio, the secondary circulation was caused in the upper liquid.

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Numerical investigation of the turbulent structure in periodic pipe flow

Hideo Udagawa and Tatsuo Sawada

ASME PVP-Vol.414-2, Emerging Technologies in Fluids, Structures, and Fluid/Structure Interactions (ASME)     99-105 2000.07

Research paper (international conference proceedings), Joint Work, Accepted

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円管内振動流をDNSによって解析を行い，特に壁近傍の乱流特性を明らかにした。

Visualization of clustering on non-magnetic and ferromagnetic particles in magnetic fluids

Tatsuo Sawada, Hiroshige Kikura, Gentaro Yamanaka, Mitsuo Matsuzaki, Isao Nakatani and Masanori Aritomi

Proceedings of SPIE Conference on Optical Diagnostics for Fluids /Heat/Combustion and Photomechanics for Solids (The International Society for Optical Engineering)  3783   389-396 1999.10

Research paper (international conference proceedings), Joint Work

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Micro-cluster formation of the non-magnetic and ferromagnetic particles in a magnetic fluid was investigated. Using an optical microscope system with cardioid condenser lens, real-time visualization of the Brownian motions of both particles were carried out. The chain-like cluster formation of both particles were observed simultaneously under the magnetic field. Two types of magnetic fluid of a water-based and kerosene-based magnetic fluids were used as test liquids.

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Shape oscillations of magnetic liquid columns subject to vertical vibrations

Motoyoshi Ohaba, Tuneyoshi Sugimoto, Tatsuo Sawada, Takahiko Tanahashi and Seiichi Sudo

Proceedings of the 3rd ASME/JSME Joint Fluids Engineering Conference (ASME)  FED-248 1999.07

Research paper (international conference proceedings), Joint Work, Accepted

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Shape oscillations of magnetic liquid columns subject to vertical vibration in a uniform magnetic field are examined in the presence of gravity. A magnetic liquid column is formed vertically against gravity in an axial magnetic field produced by Helmholtz coils and then vibrated to produce axisymmetric oscillations. A high-speed video camera is used to observe the column's dynamic shape and two high-resolution laser displacement detectors measure the amplitudes of both the exciter table and the column interface. The experimental interfacial amplitude shows good agreement with our theoretical predictions. Two new wave motions are observed: a progressive wave near the resonance range of the fundamental mode (0,1), and a mode (4,1) azimuthal one-half subharmonic oscillation beyond the mode (0,1) frequency. These are the first observations of such wave motions in a terrestrial experiment and may suggest similar liquid column oscillations in a microgravity environment.

Velocity profile measurements of magnetic fluid flow using ultrasonic Doppler method

Hiroshige Kikura, Yasushi Takeda and Tatsuo Sawada

Journal of Magnetism and Magnetic Materials (Elsevier)  201 ( 1-3 ) 276-280 1999.07

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0304-8853

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In the present study, successful applications of the ultrasound velocity profile measuring technique to velocity fields of a magnetic fluid are presented. After a brief introduction of its principle, various examples applied for the magnetic fluid flow are demonstrated.

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Oscillations of magnetic liquid columns subject to random vibration

Motoyoshi Ohaba, Tsuneyoshi Sugimoto, Tatsuo Sawada, Seiichi Sudo and Takahiko Tanahashi

Journal of Magnetism and Magnetic Materials (Elsevier)  201 ( 1-3 ) 293-296 1999.07

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0304-8853

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The interfacial impulse response of the axisymmetric mode (0,1) of a finite liquid column in a microgravity environment is simulated using magnetic liquids and random vibration.

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Dynamic characteristic of a magnetic fluid column formed by magnetic field

Nobuaki Omura, Katsuhiro Yamashita, Tatsuo Sawada and Motoyoshi Ohaba

Journal of Magnetism and Magnetic Materials (Elsevier)  201 ( 1-3 ) 297-299 1999.07

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0304-8853

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This paper examines the dynamic characteristics of liquid columns when lateral sinusoidal vibration is applied. The first, second and third resonant frequencies shift to a higher frequency region as the magnetic field intensity increases. For a magnetic fluid column, the second and third resonant frequencies show interesting behavior as the magnetic field is varied.

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Kinematic characteristics of magnetic fluid sloshing in a rectangular container subject to non-uniform magnetic fields

Tatsuo Sawada, Hiroshige Kikura and Takahiko Tanahashi

Experiments in Fluids (Springer)  26 ( 3 ) 215-221 1999.02

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0723-4864

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The dynamic behavior of a magnetic fluid in a laterally vibrated rectangular container subject to a non-uniform vertical magnetic field has been investigated. Flow behavior was observed using the ultrasound velocity profile measuring technique. The effect of the magnetic field on the resonant frequency of the fluid-container system is discussed. Experimental results are compared with the results obtained from nonlinear theory using the perturbation method.

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Magnetic field effects on axisymmetrically oscillating magnetic liquid columns

Motoyoshi Ohaba, Tsuneyoshi Sugimoto, Tatsuo Sawada, Seiichi Sudo and Takahiko Tanahashi

Journal of Japan Society of Micrograbity Application (Japan Society of Micrograbity Application)  15 ( SupplementII ) 243-248 1998.12

Research paper (scientific journal), Joint Work, Accepted

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磁性流体の液柱の軸対称振動におよぼす磁場の効果を調べた。

Kinematic characteristics of magnetic fluid sloshing in a rectangular container subject to non-uniform magnetic fields

Tatsuo Sawada, Hiroshige Kikura and Takahiko Tanahashi

PSI Proceedings 98-01, Selected Papers of the First International Symposium on Ultrasonic Doppler Methods in Fluid Mechanics and Fluid Engineering (Paul Scherrer Institut)     207-227 1998.08

Research paper (conference, symposium, etc.), Joint Work

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The dynamic behavior of a magnetic fluid in a laterally vibrated rectangular container subject to a non-uniform vertical magnetic field has been investigated. Flow behavior was observed using the ultrasound velocity profile measuring technique. The effect of the magnetic field on the resonant frequency of the fluid-container system is discussed. Experimental results are compared with the results obtained from nonlinear theory using the perturbation method.

Magnetic field effects on wave motion of a magnetic liquid

Motoyoshi Ohaba, Masatsugu Tomonori, Tatsuo Sawada, Seiichi Sudo and Takahiko Tanahashi

Studies in Applied Electromagnetics and Mechanics, Nonlinear Electromagnetic Systems 13   855-858 1998.07

Research paper (international conference proceedings), Joint Work, Accepted

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磁性流体液柱が振動する場合に液柱表面に生じる表面波動の様子を実験的に調べて，印加磁場と加振周波数との関係を明らかにした。

Axisymmetric oscillation of magnetic liquid columns in a magnetic field

Motoyoshi Ohaba, Tatsuo Sawada, Masatsugu Tomonori, Seiichi Sudo and Takahiko Tanahashi

Studies in Applied Electromagnetics and Mechanics, Nonlinear Electromagnetic Systems 13   863-866 1998.07

Research paper (international conference proceedings), Joint Work, Accepted

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軸対象モードでの磁性流体液柱の振動特性を調べ，理論解析結果との比較検討を行った。

Lateral vibration of a magnetic fluid column

Tatsuo Sawada, Yasuhiro Fujiwara, Nobuaki Omura, Motoyoshi Ohaba and Takahiko Tanahashi

Studies in Applied Electromagnetics and Mechanics, Nonlinear Electromagnetic Systems 13   871-874 1998.07

Research paper (international conference proceedings), Joint Work, Accepted

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Dynamic behavior of a magnetic fluid column which is formed between two electromagnets is investigated. An electrodynamic shaker is used to generate a lateral sinusoidal vibration. Experiments are carried out to clarify the influence of magnetic field intensity, column height and fluid volume on the vibration of a magnetic fluid column. A theoretical approach is also taken using linearized wave theory. The first resonant frequency of displacement of the free surface increases with the magnetic field intensity, and decreases with the radius and height of the magnetic fluid column. These results are in good agreement with theoretical results.

Ultrasound velocity profile measurement of a magnetic fluid flow caused by rotating magnetic field

Takahiro Handa, Tatsuo Sawada and Gentaro Yamanaka

Proceedings of the 1998 ASME Fluid Engineering Division Summer Meeting (ASME)  FED-245 1998.06

Research paper (international conference proceedings), Joint Work, Accepted

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Magnetic fluid is a stable suspension of solid magnetic particles and is an opaque fluid. This paper presents an application of the Ultrasound Velocity Profile monitor in measuring flow of a magnetic fluid in a cylindrical container. Velocity profiles of rotating flow of a magnetic fluid caused by an applied magnetic field were measured by UVP method and the 3-D flow structure was clarified.

Magnetic fluid simulation of liquid column oscillations in microgravity

Motoyoshi Ohaba, Yu Zhou Liu, Tatsuo Sawada and Takahiko Tanahashi

Proceedings of the 1998 ASME Fluid Engineering Division Summer Meeting (ASME)  FED-245 1998.06

Research paper (international conference proceedings), Joint Work, Accepted

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磁性流体液柱を用いた微小重力場での液柱振動現象の模擬実験を行った。そして，その模擬実験の有効性を明らかにした。

Axisymmetric interfacial oscillations of a magnetic fluid column

Motoyoshi Ohaba, Tatsuo Sawada, Shinpachiro Saito, Seiichi Sudo and Takahiko Tanahashi

JSME International Journal, Ser.B (JSME)  41 ( 2 ) 511-517 1998.05

Research paper (scientific journal), Joint Work, Accepted

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This paper presents the stability and dynamic characteristics of an axisymmetrically oscillating magnetic liquid column subjected to a uniform magnetic field in the presence of gravity. Initially, the axisymmetric mode response of a magnetic liquid column is analyzed using potential theory based on a magnetic field perturbation method. Then, an experiment is described in which a liquid column is formed between Helmholtz coils and vibrated vertically to produce axisymmetric oscillations by an electodynamic exciter. The surface frequency response of the column is measured optically using a high-speed video camera, a strobovision-snalyzer and a stroboscope. The results show that the magnetic field exerts a stabilizing effect on the column and the resonance frequency increases for increased liquid column aspect ratio(diameter / height). Both the experimental interfacial response and resonance frequency show good agreement with the theoretical prediction.

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Lateral vibrational characteristics of a magnetic liquid column held by magnetic field

Motoyoshi Ohaba, Tatsuo Sawada, Shin-Hachiro Saito, Seiichi Sudo, Takahiko Tanahashi

Transactions of the Japan Society of Mechanical Engineers Series B (Japan Society of Mechanical Engineers)  63 ( 612 ) 2725-2731 1997.08

Research paper (scientific journal), Joint Work, Accepted

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We have investigated the stability and vibrational response of magnetic liquid columns held by Helmholtz coils. Theoretical resonance frequencies were derived from the linear potential theory prior to the experiment. During the experiment, a small quantity of a kerosene-based magnetic liquid was injected onto a lower pole plate. When the magnetic field was increased. a cylindrical column (height=9.78mm) was vertically formed between the two pole faces of the iron core Helmholtz coils. When the magnetic field was decreased, the column diameter exhibited hysteresis such that the column broke at a smaller diameter than that at formation. The coils holding the liquid column were then excited horizontally and the lowest mode (m=1, n=1) derived theoretically appeared in the measurements. The surface frequency response was measured optically using a CCD camera, a strobovision analyzer and a stroboscope for various magnetic field intensities and aspect ratios (mean diameter/height). We found that the resonance frequency of the mode (m=1, n=1) decreased with increase of the aspect ratio. The experimental resonance frequencies were in qualitative agreement with the theoretical predictions.

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