2004 Fiscal Year Final Research Report Summary
Dependence of ultrasonic propagation properties of functional fluids on cluster formation
| Project/Area Number |
14550158
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Fluid engineering
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| Research Institution | Keio University |
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Principal Investigator |
SAWADA Tatsuo Keio University, Faculty of Science and Technology, Professor, 理工学部, 教授 (00162545)
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| Project Period (FY) |
2002 – 2004
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| Keywords | Magnetic Fluid / MR Fluid / Functional Fluid / Cluster / Ultrasonic Wave / Sound Velocity / Magnetic Field |
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| Research Abstract |
Ultrasonic propagation velocities in water-based and kerosene-based magnetic fluids and in an MR fluid under uniform magnetic field are investigated experimentally. Measurements of ultrasonic propagation velocity are carried out while measuring the elapsed time of magnetic field application and while varying the magnetic field intensity and the angle between the direction of ultrasonic propagation and the direction of the magnetic field. The ultrasonic propagation velocity changes with the elapsed time and intensity of an external magnetic field because of the formation of clusters. In varying the angle of the applied magnetic field, anisotropy of the ultrasonic propagation velocity is observed, In HC-50, the percentage change of ultrasonic propagation velocity with applied magnetic field is smaller than that in W-40. It seems that the chain-like clusters formed in HC-50 are smaller than those in W-40. These interesting results are believed to be dependent on characteristic rheological properties of magnetic fluids that are related to surfactants that are applied to the particles. The percentage change of ultrasonic propagation velocity in the MR fluid is one order of magnitude larger than that in magnetic fluids and is observed abruptly with the application of the magnetic field.
We obtained several interesting experimental results related to ultrasonic propagation velocities. These results have not been predicted by previous theoretical approaches. At the present stage, it is necessary to carry out more various and detailed experiments to clarify the mechanisms producing these ultrasonic propagation properties in magnetic and MR fluids.
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