Influence of size on anisotropic thermophysical properties of magnetic suspensions

Article type: Research Article

Authors: Iwamoto, Yuhiro^a; | Kondoh, Syuhei^a | Ido, Yasushi^a | Yamamoto, Hisashi^b | Nishida, Hitoshi^b | Yamasaki, Haruhiko^c | Yamaguchi, Hiroshi^c | Jeyadevan, Balachandran^d

Affiliations: [a] Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Aichi, 466-8555, Japan | [b] National Institute of Technology, Toyama College, 13 Hongo Toyama-city, Toyama, 939-8630, Japan | [c] Department of Mechanical Engineering, Doshisha University, Kyotanabe, Kyoto, 610-0321, Japan | [d] Department of Engineering, The University of Shiga Prefecture, 2500, Hassaka-cho, Hikone, Shiga, 522-8533, Japan

Correspondence: [*] Corresponding author: Yuhiro Iwamoto, Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Room 904, Building #3, Gokiso-cho, Showa-ku, Nagoya, Aichi, 466-8555, Japan. Tel.: +81 52 735 7542; Fax:+81 52 735 5442; E-mail: iwamoto.yuhiro@nitech.ac.jp

Abstract: Thermophysical and rheological properties of magnetic suspensions, in which nm- and/or μm-sized magnetic particles disperse, are tunable by applying a magnetic field externally. In the present study, the influence of the size of magnetic particles on the thermophysical and rheological properties was investigated. Four types of the magnetic suspensions were prepared with varying the volume fractions of nm- and μm-sized magnetic particles. The total fraction of the magnetic particles in all samples was adjusted to be 6 vol.%. The thermal conductivity in the presence of homogeneous magnetic field was measured by the originally-designed transient hot-wire method (TPSY02, CLIMA-TEC). And the steady-state rheological behaviors were investigated by a magnetorheometer (MCR302, Anton-paar). As the obtained results, the thermal conductivity was enhanced when the magnetic field was applied parallel to the temperature gradient for all samples. On the other hand, the thermal conductivity decreased when the magnetic field was applied perpendicular to the temperature gradient in the case that both the nm- and μm-sized magnetic particles were dispersed. It was also found that the fluid only with the nm-sized magnetic particles showed a Newtonian-like behavior even in the presence of magnetic field. When the μm-sized magnetic particles were mixed and the fraction increased, the rheological behavior changed from Newtonian to viscoplastic fluid.

Keywords: Magnetic suspension, magnetic fluid, MR fluid, bidisperse MR fluid, thermal conductivity, steady-state rheological behavior

DOI: 10.3233/JAE-180048

Journal: International Journal of Applied Electromagnetics and Mechanics, vol. 58, no. 3, pp. 371-385, 2018