2302 印加磁場による磁性流体,MR流体中の超音波伝播速度への影響(S42-1 複雑流体の流動現象(1),S42 複雑流体の流動現象)  [in Japanese] 2302 Influence of External Magnetic Field on Ultrasonic Propagation Velocity in Magnetic and MR Fluids  [in Japanese]

The properties of ultrasonic propagation velocity in water-based and kerosene-based magnetic fluids and an MR fluid are examined experimentally. The ultrasonic measurement scheme is based on the pulse method. The external magnetic field intensity is varied from 0mT to 550mT 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 changes with the elapsed time of external magnetic field application and with magnetic field intensity. Moreover, the ultrasonic propagation velocity in MR fluid is larger than that in magnetic fluids. These 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).