Presentations -

Liquid sloshing and swirling in a rotating, laterally oscillating cylindrical container

Yusuke Saito, Eisaku Yokose and Tatsuo Sawada

VSJ Meeting (Muroran 2017) (Muroran) , 

2017.11

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Oral presentation (general), The Visualization Society of Japan

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水平直線方向に振動しながら垂直軸回りを回転する円筒容器内の液体の挙動を調べた。円筒容器内壁に設置した圧力センサで水圧を測定することで，スロッシングが生じた時の液体の自由表面の変位を調べた。スワーリング発生時に圧力センサが測定した水圧変動をFFT解析した。その結果から，容器の回転方向に対して同じ方向と逆方向に回転する２種類の波が同時に存在し，その大小関係によって見かけ上のスワーリングの方向が決まるという事を明らかにした。

Frequency dependence on ultrasonic propagation in MR fluids under oscillating magnetic fields

Takashi Fukumoto, Yuya Tanaka and Tatsuo Sawada

26th MAGDA Conference in Kanazawa (Kanazawa) , 

2017.10

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Oral presentation (general), The Japan Society of Applied Electromagnetics and Mechanics

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MR流体に様々な周波数の振動磁場を印加した時に形成されるクラスタの変化を超音波伝播速度を用いて評価した。振動磁場周波数の2倍の周波数でクラスタの形成崩壊が繰り返されることが確認された。

Magnetic fluid flow under DC and AC magnetic fields

Yuta Itahashi, Ryutaro Hirano and Tatsuo Sawada

The 18th International Symposium on Applied Electromagnetics and Mechanics (Chamonix) , 

2017.09

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Poster presentation, Ecole des Mines de Paris

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This study reports magnetic fluid flow in a square duct under DC, AC, and DC+AC magnetic fields. We measured pressure drop with applying different magnetic fields. Under magnetic fields, flow resistance increased by forming a cluster so that pressure drop and friction factor also increased. From FFT analysis of the pressure drop, we obtained different power spectrum for AC and DC+AC magnetic fields.

Change of ultrasonic propagation velocity in MR fluid under AC magnetic fields

Takashi Fukumoto, Yuya Tanaka and Tatsuo Sawada

The 18th International Symposium on Applied Electromagnetics and Mechanics (Chamonix) , 

2017.09

, 

Poster presentation, Ecole des Mines de Paris

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This paper presented experimental investigation about MR fluid under AC magnetic fields. Clusters in MR fluid are formed along magnetic fields. Clustering structures in MR fluid make ultrasonic propagation velocity change. We investigated clustering structures by measuring ultrasonic propagation velocity. As a result, the clusters in MR fluid have dependence on elapsed time, strength, frequency and angle of AC magnetic fields.

The resistance force of a magneto-rheological shock absorber under a magnetic field

Takuma Endo, Sou Aoki and Tatsuo Sawada

The 18th International Symposium on Applied Electromagnetics and Mechanics (Chamonix) , 

2017.09

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Poster presentation, Ecole des Mines de Paris

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This study reports the theoretical and experimental resistance force of MR fluid in a pipe that changes depending on a magnetic field. We used Bingham plastic model to represent the dynamic behavior of MR fluid flow in a circular pipe under a magnetic field theoretically. Analytical results indicate that the radius of a pipe has a major effect on the resistance force. We conducted the drop impact test to verify our theoretical approach. The resistance force of MR shock absorber was changed depending on a magnetic field and the radius of the pipe as indicated in theoretical results. We also conducted the flow experiment of MR fluid at a constant flow rate and compared experimental results and analytical results quantitatively.

Changes in the resistance force of a magneto-rheological shock absorber induced by a magnetic field

Tatsuo Sawada, Takuma Endo, Yuzo Shimizu and Hitoshi Nishida

The 10th Japanese-Mediterranean Workshop on Applied Electromagnetic Engineering for Magnetic, Superconducting and Nano Materials (Izmir) , 

2017.07

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Oral presentation (general), Izmir Institute of Technology

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The magnetic particles in an MR fluid form clusters parallel to the direction of the applied magnetic field, and yield stress is generated. As a result, the apparent viscosity of the MR fluid increases. In the present paper, we propose a theoretical approach for obtaining the resistance force controlled by the magnetic field using an MR flow model. We use a mechanical model of an MR fluid pipe flow with a tapered pin. Moreover, we conduct some experiments to test our theoretical approach.

Ultrasonic propagation velocity in a MR fluid under alternating magnetic fields

Yuya Tanaka, Takashi Fukumoto Tatsuo Sawada

The 29th Symposium on Electromagnetics and Dynamics (Kurashiki) , 

2017.05

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Oral presentation (general), JSAME

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When an external magnetic field is applied to a MR fluid, particles get together and clusters appear along the magnetic fields. These phenomena influence on the velocity of ultrasonic propagation. We changed the frequency and strength of the magnetic field and measured the change of the propagation velocity due to external magnetic fields with several directions. We confirmed the anisotropy of ultrasonic propagation velocity and estimated the structure of cluster formation in a MR Fluids under alternating magnetic fields.

New calculation technique for the attitude of hull combined by knockdown pontoons

Yujik Doya and Tatsuo Sawada

2016 Hong Kong International Conference on Engineering and Applied Sciences (Hong Kong) , 

2016.12

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Poster presentation, Higher Education Forum

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Knockdown pontoons are often used in work vessels during construction. The typical shape of their modules is cuboidal, and these modules are combined into one hull. We proposed a new easy-to-operate technique to calculate the attitude of the floating body with various shapes and/or large inclined angles. The calculated results were compared with the experimental results of this technique.

Liquid sloshing in a rotating, laterally oscillating cylindrical container

Yusuke Saito and Tatsuo Sawada

2016 Hong Kong International Conference on Engineering and Applied Sciences (Hong Kong) , 

2016.12

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Poster presentation, Higher Education Forum

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Free surface movement of water in a rotating, laterally oscillating cylindrical container was qualitatively investigated. Time-dependent dynamic pressure was measured instead of free surface displacement. The swirling direction was determined by forcing the frequency and rotating direction of the cylindrical container. The swirling direction was opposite to that of the rotating cylindrical container when the forcing frequency was less than the resonant frequency, whereas the crest of the free surface swirled in the same direction as that of the rotating cylindrical container when the forcing frequency greatly increased. Unstable swirling occurred at the resonant frequency, but it disappeared as the rotating frequency increased.

Magnetic fluid flow in a square duct under oscillating magnetic field

Yuta Itahashi, Ryutaro Hirano and Tatsuo Sawada

Japanese Symposium on Magnetic Fluids (Sapporo) , 

2016.12

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Oral presentation (general), Magnetic fluid flow in a square duct under oscillating magnetic field

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Magnetic fluid flow in a square duct under magnetic fields has been studied by an experimentally. We measured pressure drop with applying DC, AC and DC+AC magnetic fields. Flow resistance increased under magnetic fields so that pressure drop and friction factor increased. From FFT analysis of the pressure drop, we obtained different power spectrum for AC and DC+AC.

Ultrasonic propagation velocity change in MR fluids under AC magnetic fields

Takashi Fukumoto, Yuya Tanaka and Tatsuo Sawada

25th MAGDA Conference in Kiryu (Kiryu) , 

2016.11

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Oral presentation (general), The Japan Society of Applied Electromagnetics and Mechanics

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MR流体に異なる周波数の交流磁場を印加した時に形成されるクラスタの変化を超音波伝播速度を用いて評価した。結果として、交流磁場周波数の2倍の周波数でクラスタの形成崩壊が繰り返されることが確認された。

Flow of magnetic fluid in a square duct under oscillating magnetic field

Yuta Itahashi, Shinya Kondo and Tatsuo Sawada

The 28th Symposium on Electromagnetics and Dynamics (Yokohama) , 

2016.05

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Oral presentation (general), JSME

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Magnetic fluid flow in a square duct under fields was investigated experimentally. We used DC, AC and DC+AC magnetic fields. Pressure drop in a test section was measured and influence of magnetic fields on flow resistance was discussed. Periodic pressure drop was investigated by FFT analysis. Different power spectra for AC and DC + AC were obtained.

The damping force of a magnetorheological shock absorber depending on a magnetic field

Takuma Endo, Yuzo Shimizu and Tatsuo Sawada

The 28th Symposium on Electromagnetics and Dynamics (Yokohama) , 

2016.05

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Oral presentation (general), JSME

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This study reports the theoretical damping force of a magnetorheological (MR) shock absorber depending on a magnetic field. We used Bingham plastic model to represent the dynamic behavior of MR fluid flow in a circular pipe with tapered metering pins under a magnetic field theoretically. Since MR fluid has yield stresses, the flow is divided into two regions; shear and plug flows. We revealed the relationship between the damping force of MR shock absorber and an applied magnetic field. Analytical results indicated that the radius of a pipe and the velocity of the piston effect on the damping force. We conducted drop impact tests and compared experimental results with analytical results. The comparison results indicated that the effect of magnetic field on the damping force depends on the development of the flow, and that the effect increases in a developing flow.

Ultrasonic propagation velocity change in MR fluids under oscillating magnetic fields

Takashi Fukumoto, Kazuma Murata and Tatsuo Sawada

The 28th Symposium on Electromagnetics and Dynamics (Yokohama) , 

2016.05

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Oral presentation (general), JSME

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This paper reports experimental analysis of magnetorheological fluid (MR fluid) under oscillating magnetic fields. The experiments were carried out under oscillating magnetic fields. As a result, clusters in MR fluids have dependence of intensity and frequency of oscillating magnetic fields. The frequency of ultrasonic propagation velocity change is twice the frequency of oscillating magnetic fields.

Heat transfer characteristics of magnetic fluid under the influence of magnetic field in turbulent flow region

Kosuke Takeda, Masaaki Motozawa, Tatsuo Sawada and Haruo Kawaguchi

Japanese Symposium on Magnetic Fluids (Hamamatsu) , 

2015.12

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Oral presentation (general), 磁性流体研究連絡会

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乱流領域における磁場影響下での磁性流体強制対流熱伝達について実験的に研究を行った。磁場強度とRe数を用いた無次元数Mhを提案し，伝熱の抑制やその回復距離をMh数によって整理した。

The effect of AC magnetic fields on ultrasonic propagation velocity in MR fluids

Takashi Fukumoto, Kazuma Murata and Tatsuo Sawada

Japanese Symposium on Magnetic Fluids (Hamamatsu) , 

2015.12

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Oral presentation (general), 磁性流体研究連絡会

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MR流体に交流磁場を印加し，超音波伝播速度を測定することで，クラスタ形成を評価した。10 mT，30 mT，50 mTの交流磁場を1，2，3 Hzの周波数でそれぞれ印加し，計測を行った。結果として，クラスタ形成には時間依存性，磁場強度依存性，周波数依存性があることが確認できた。

The damping force of a magnetorheological shock absorber changed by a magnetic field

Takuma Endo, Yuzo Shimizu and Tatsuo Sawada

24th MAGDA Conference in Tohoku (Sendai) , 

2015.11

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Oral presentation (general), The Japan Society of Applied Electromagnetics and Mechanics

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This study reports the theoretical damping force of a magnetorheological (MR) shock absorber changed by a magnetic field. We used Bingham plastic model to represent the dynamic behavior of MR fluid flow in a circular pipe under a magnetic field theoretically. Since MR fluid has yield stresses, the flow is divided into two regions; shear and plug flows. We revealed the relationship between the damping force of MR shock absorber and an applied magnetic field. Analytical results indicated that the radius of a pipe and the velocity of the piston affect on the damping force.

Ultrasonic propagation velocity in functional magnetic fluids under AC magnetic fields

Kazuma Murata, Takashi Fukumoto and Tatsuo Sawada

JSME Fluids Engineering Conference 2015 (Tokyo) , 

2015.11

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Oral presentation (general), JSME

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The properties of ultrasonic propagation velocity in MR fluids (MRF122-EG and MRF132-DG) are studied experimentally.We measured ultrasonic propagation velocity with the pulse method. We used AC magnetic fields with the frequency of 1 Hz and 2 Hz, and the intensity of 50 mT and 75 mT.The change of cluster formation were confirmed by applying different frequency or magnetic flux density.

Shock absorption in magnetorheological damper with tapered pin

Yuzo Shimizu, Shintaro Takagi and Tatsuo Sawada

The 17th International Symposium on Applied Electromagnetics and Mechanics (Kobe) , 

2015.09

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Poster presentation, The Japan Society of Applied Electromagnetics and Mechanics

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We proposed a mechanical model of MR fluid pipe flow and compared with the experiment results of the flow under an impact load, and conducted drop impact tests with four types of tapered metering pins and qualitative analysis of effects of the pins. The results show that the shape of the pins has some effect on the entire shock absorption process whereas magnetic field strength affects the post-peak behavior only, and shock absorption with a longer tapered pin is more widely controllable by magnetic field.

Suppression of heat transfer of turbulent magnetic fluid flow by applying uniform magnetic field

Kosuke Takeda, Masaaki Motozawa, Mitsuhiro Fukuta, Yasuo Kawaguchi and Tatsuo Sawada

The 17th International Symposium on Applied Electromagnetics and Mechanics (Kobe) , 

2015.09

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Oral presentation (general), The Japan Society of Applied Electromagnetics and Mechanics

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Forced convective heat transfer of turbulent magnetic fluid flow is remarkably suppressed by applying magnetic field. The result shows that the suppression becomes stronger by applying stronger magnetic field, but is saturated at a certain strength of magnetic field. This suppression depends on not only magnetic field intensity but also flow condition. The relationship among heat transfer, magnetic field intensity and flow condition was discussed.