Details of a Researcher - Sawada, Tatsuo

Papers - Sawada, Tatsuo

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Experimental measurements of ultrasonic propagation velocity and attenuation in a magnetic fluid

Masaaki Motozawa, Yuta Iizuka and Tatsuo Sawada

Journal of Physics: Condensed Matter (IOP Publishing) 20 ( 20 ) 204117(5pp) 2008.05

Research paper (scientific journal), Joint Work, Accepted, ISSN 0953-8984

The ultrasonic propagation velocity and attenuation in a magnetic fluid subjected to the magnetic field are measured precisely. Various characteristic properties of ultrasonic propagation in magnetic fluid
such as hysteresis and anisotropy are observed. These results show that the ultrasonic propagation velocity and attenuation are dependent upon the intensity and the length of time that the magnetic field is applied. When the magnetic field is applied, some of the magnetic particles in the magnetic fluid form clustering structures that influence ultrasonic propagation in a magnetic fluid.

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Properties of ultrasonic propagation in functional fluids under magnetic fields

Masaaki Motozawa, Tatsuo Sawada and Yoshiyuki Matsumoto

International Journal of Modern Physics B (World Scientific) 21 ( 28-29 ) 4914-4921 2007.11

Research paper (scientific journal), Joint Work, Accepted

The properties of ultrasonic propagation velocity in water-based and kerosene-based magnetic fluids and an MR fluid are examined experimentally. The ultrasonic frequency used is 1 MHz and the measurement scheme is based on the pulse method. The external magnetic field intensity is varied from 0 mT to 550 mT and is swept at a constant rate dB/dt (sweep rate). The ultrasonic propagation velocity changes with applied magnetic field and hysteresis is observed. The properties of ultrasonic propagation seem to be highly influenced by the formation of chain-like clusters (in the magnetic fluids) and robust clusters (in the MR fluid).

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Characteristics of a tuned liquid damper using a magnetic fluid

Ken-ichi Ohno, Manabu Shimoda and Tatsuo Sawada

Proceedings of the 10th International Conference on Electrorheological Fluids and Magnetorheological Suspensions (World Scientific Publishing/University of Nevada, Reno) 459-466 2007.11

Research paper (international conference proceedings), Joint Work

The frequency response of a tuned liquid damper (TLD) which uses the sloshing of a magnetic fluid (a tuned magnetic fluid damper (TMFD)) is investigated. Effective mass, stiffness and damping are estimated from experimental results, using a single-degree-of-freedom tuned mass damper (TMD) analogy. TLD is a passive mechanical damper that uses sloshing liquid to dampen oscillations, but TMFD is semi-active damper because of application of magnetic field. We first compare results obtained by numerical simulation and experiment to show that a TMFD cannot be modeled by a simple analytical model based on analogy with TMD. Then we propose a new analytical model of TMFD and examine the validity of this new model experimentally.

Properties of ultrasonic propagation in functional fluids under magnetic fields

Masaaki Motozawa and Tatsuo Sawada

Proceedings of the 10th International Conference on Electrorheological Fluids and Magnetorheological Suspensions (World Scientific Publishing/University of Nevada, Reno) 248-255 2007.11

Research paper (international conference proceedings), Joint Work

Two-layered magnetic fluid sloshing in a rectangular container

Shin-ichi Yoshida, Andrea Benvenuti, Kenji Tomita and Tatsuo Sawada

Proceedings of the 10th International Conference on Electrorheological Fluids and Magnetorheological Suspensions (World Scientific Publishing/University of Nevada, Reno) 551-556 2007.11

Research paper (international conference proceedings), Joint Work

The dynamic behavior of a two-layered fluid in a laterally oscillated rectangular container under a vertical nonuniform magnetic field was studied experimentally. The two-layered fluid was formed of water based magnetic fluid and silicone oil. The dynamic behavior was studied by measuring the velocity profile of the two-layered fluid using an ultrasound velocity profile measuring technique while varying the vertical magnetic field. The displacement of the free surface was measured using a laser sensor. The effect of the magnetic field on the sloshing of the two-layered fluid was considered.

Ultrasonic analysis of clustering structures in magnetic fluid under magnetic field

Masaaki Motozawa, Yuta Iizuka and Tatsuo Sawada

International Conference on Advanced Technology in Experimental Mechanics 2007 (The Materials & Mechanics Division of JSME) 1-5 2007.09

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

Experimental results from studies on the properties of ultrasonic propagation velocity and attenuation in hydrocarbon-based magnetic fluid are reported. The ultrasonic frequency used is 2 MHz and the measurement scheme is based on the pulse method. The external magnetic field intensity is varied from 0 to 550 mT and the angle between the magnetic field direction and the direction of ultrasonic wave propagation is adjusted from 0 to 90°. The ultrasonic propagation velocity and attenuation changes are dependent upon the intensity of the magnetic field and the elapsed time of application. Characteristic properties of ultrasonic propagation in magnetic fluid are observed. These particular results seem to be caused by clustering structures in the magnetic fluid. Based on these results, the inner structure of the magnetic fluid is analyzed experimentally and the application of non-contact inspection in opaque fluids by ultrasonic techniques is discussed.

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Characteristic parameters of a tuned magnetic fluid damper under magnetic fields

Ken-ichi Ohno, Manabu Shimoda and Tatsuo Sawada

Proceedings of FEDSM2007, 5th Joint ASME/JSME Fluids Engineering Conference (ASME) 1-4 2007.08

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

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Investigation of inner structure in magnetic and MR fluids by ultrasonic propagation velocity

Masaaki Motozawa, Yuta Iizuka and Tatsuo Sawada

Proceedings of FEDSM2007, 5th Joint ASME/JSME Fluids Engineering Conference (ASME) 1-6 2007.07

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

When the magnetic field is applied to magnetic or MR fluids, some of inner particles form clustering structure. These clustering structures influence on the ultrasonic propagation velocity in these fluids. We measured precisely the properties of ultrasonic propagation velocity in these fluids subjected to the magnetic field. The measurement scheme is based on the pulse method. The external magnetic field intensity is varied from 0 mT to 550 mT and the angle between the magnetic field direction and the direction of ultrasonic wave propagation is varied from 0° to 90°. Some interesting properties of ultrasonic propagation such as hysteresis and anisotropy are observed. Based on the experimental results, the inner structures of the magnetic or the MR fluids are analyzed experimentally and the application of non-contact inspection in these fluids by ultrasonic techniques is discussed.

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Experimental measurement of ultrasonic propagation velocity and attenuation in magnetic fluids

Masaaki Motozawa, Yuta Iizuka and Tatsuo Sawada

The 12th Japanese-French Workshop on Magnetic Fluids (University Pierre et Marie Curie - Paris 6) 2007.07

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

Influence of a uniform magnetic field on ultrasonic propagation velocities in magnetic fluids

Masaaki Motozawa, Yoshiyuki Matsumoto and Tatsuo Sawada

International Journal of Applied Electromagnetics and Mechanics (IOS Press) 25 ( 1-4 ) 133-138 2007.05

Research paper (scientific journal), Joint Work, Accepted, ISSN 1383-5416

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Effective method of applying magnetic field on a tuned liquid damper using a magnetic fluid

Shohei Horie, Manabu Shimoda, Ken-ichi Ohno, Jun Nakamura and Tatsuo Sawada

International Journal of Applied Electromagnetics and Mechanics (IOS Press) 25 ( 1-4 ) 139-143 2007.05

Research paper (scientific journal), Joint Work, Accepted, ISSN 1383-5416

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Influence the chain-like cluster in a magnetic fluid on velocity profiles of the oscillating pipe flow

Ryo Hasegawa, Takashi Innami, Manabu Shimoda and Tatsuo Sawada

Journal of the Japan Society of Applied Electromagnetics and Mechanics (The Japan Society of Applied Electromagnetics and Mechanics) 14 ( 1 ) 21-26 2006.03

Research paper (scientific journal), Joint Work, Accepted, ISSN 0919-4452

Oscillating pipe flow of a magnetic fluid subject to a magnetic field was investigated experimentally. Time-dependent velocity profiles are obtained by UVP method. When the magnetic field is applied for some period before measurement, peculiar velocity profiles are obtained because of the growth of chain-like clusters in the magnetic fluid. The influence of the amount of time of pre-applying magnetic field and magnetic field intensity on flow behaviors are examined. The apparent flow rate is introduced to evaluate the correlation between the velocity profile and the growth of chain-like clusters. It is found that the rate of change of the apparent flow rate increases with both magnetic field intensity and the pre-application time of magnetic field.

Effect of external magnetic field on ultrasonic propagation velocity in magnetic fluids

Masaaki Motozawa, Yoshiyuki Matsumoto and Tatsuo Sawada

JSME International Journal, Ser.B (JSME) 48 ( 3 ) 471-477 2005.08

Research paper (scientific journal), Joint Work, Accepted

Experimental results for the properties of ultrasonic propagation velocity in kerosene-based and water-based magnetic fluids are reported. The ultrasonic propagation velocity in magnetic fluids is dependent on temperature, elapsed time of applying the magnetic field, and magnetic field intensity. Hysteresis and anisotropy of ultrasonic propagation velocity are observed. These interesting results seem to be related to chain-like cluster formation in the magnetic fluids and the characteristic period of Brownian motion of the magnetic particles.

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Influence of magnetic field on ultrasonic propagation velocity in magnetic fluids

Masaaki Motozawa and Tatsuo Sawada

Journal of Magnetism and Magnetic Materials (Elsevier) 289 ( 1-3 ) 66-69 2005.04

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

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Velocity profile measurement of an oscillating pipe flow of a magnetic fluid

Yuki Oshikawa, Takeshi Innami and Tatsuo Sawada

Proceedings of ASME FEDSM'03, 4th ASME-JSME Joint Fluids Engineering Conference (ASME) 1-7 2003.07

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

Since UVP is the method to take the velocity information by using ultrasound, this method is very suitable for measuring the velocity profile of opaque fluid. Oscillating pipe flow of a magnetic fluid was investigated experimentally to examine the applicability of this method to magnetic fluid flow. We used a diluted water-base magnetic fluid and the magnetic field was applied by two permanent magnets. Influence of an applied magnetic field on flow behaviors were discussed. The amplitude and phase of the oscillating velocity varied with intensity of the magnetic field, which yielded increase of the apparent viscosity.

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Characteristics of iltrasound propagation in a magnetic fluid under uniform magnetic field

Masaaki Motozawa and Tatsuo Sawada

Proceedings of ASME FEDSM'03, 4th ASME-JSME Joint Fluids Engineering Conference (ASME) 1-4 2003.07

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

When an external magnetic field is applied to a magnetic fluid, some of the colloidal particles coagulate and form chain-like clusters. Properties of ultrasonic propagation wave are changed by these chain-like clusters. We carried out measurement of the ultrasonic propagation velocity in a magnetic fluid. Measurement were made by changing the magnetic field intensity from 0 mT to 570 mT, and the angle between the magnetic field direction and direction of the ultrasound propagation from 0° to 180°. The ultrasound frequencies were 1 MHz, 2 MHz and 4 MHz. Some of experimental results for the characteristics of ultrasound propagation in a magnetic fluid under a uniform magnetic field were reported.

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Effect of magnetic field on a tuned liquid damper using a magnetic fluid

Yasuhiro Ohira, Hiroshi Houda and Tatsuo Sawada

International Journal of Applied Electromagnetics and Mechanics (IOS Press) 13 ( 1-4 ) 71-78 2002.12

Research paper (scientific journal), Joint Work, Accepted, ISSN 1383-5416

The frequency response of a tuned liquid damper (TLD) which uses a magnetic fluid (called a "tuned magnetic fluid damper" (TMFD)) is investigated. A single-degree-of-freedom tuned mass damper (TMD) analogy is used to define the effective mass, stiffness and damping and these parameters are then estimated from experimental results. A numerical simulation is used to examine the TMFD and appropriate magnetic field conditions for effective damping are predicted. In particular, the performance of the TMFD was improved by switching the applied magnetic field at a point near the resonant frequency of the undamped structure.

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Influence of a magnetic field on ultrasound propagation in a magnetic fluid

Tatsuo Sawada, Hiroyuki Nishiyama and Takashi Tabata

Journal of Magnetism and Magnetic Materials (Elsevier) 252 ( 1-3 ) 186-188 2002.11

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

Experimental results for anisotropy and hysteresis of the ultrasonic propagation velocity(1 MHz) in a magnetic fluid subject to a magnetic field are reported. Measurements were made by the pulse method while the magnetic field intensity was varied from 0 mT to 570 mT and the angle between the magnetic field direction and the direction of ultrasonic wave propagation was varied between 0 deg and 180 deg. Some interesting results that seem to be caused by cluster formation in the magnetic fluid were obtained.

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Nonlinear shape oscillations of axisymmetric magnetic fluid columns in a magnetic field

Motoyoshi Ohaba, Yuko Suzuki, Tatsuo Sawada, Yu-Zhou Liu, Masaaki Takeuti and Takahiko Tanahashi

Journal of Magnetism and Magnetic Materials (Elsevier) 252 ( 1-3 ) 306-308 2002.11

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

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Sloshing behavior of a magnetic fluid in a cylindrical container

Tatsuo Sawada, Yasuhiro Ohira and Hiroshi Houda

Experiments in Fluids (Springer) 32 ( 2 ) 197-203 2002.02

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

Sloshing of a magnetic fluid in a laterally vibrated cylindrical container subject to a non-uniform vertical magnetic field was examined. Internal velocity profiles were measured using ultrasound Doppler velocimetry. The effect of the magnetic field on the resonant frequency of the fluid-container system was examined and the results were compared with theoretical results. The second and third peak of the power spectra of velocity shifted to a low frequency region as the magnetic field was increased. It was observed that these derived frequency peaks were connected with swirling in the cylindrical container.

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