Control of the orientational characteristics of disk-like hematite particles by a simple shear flow

抄録

We discuss the behavior of oblate spheroidal hematite particles in a simple shear flow. Magneto-rheological properties are strongly dependent on the magnetic field direction. For instance, a rod-like hematite particle suspension exhibits negative viscosity characteristics in a certain direction of an applied magnetic field. From this background, we here consider the case of an external magnetic field applied in the direction of the angular velocity vector of a simple shear flow. If the magnetic field is much more dominant than the thermal motion, the particle can almost freely rotate about the direction of the angular velocity vector. This characteristic rotational motion is suppressed or controlled by the shear flow more significantly with increasing shear rate.