Frictional torque on an ellipsoid rotating in a uniformly magnetized ferrofluid

We analyze the frictional torques experienced by macroscopic prolate and oblate ellipsoids rotating steadily in a ferrofluid subject to a uniform magnetic field. The magnetoviscous increment in the apparent shear viscosity of the magnetic colloid is predicted to be substantially larger for oblate then for prolate ellipsoids. In each case the ellipsoid is assumed to rotate about its axis of revolution which is parallel to the external magnetostatic field.