The motion of an ellipsoid in a rotating Stokes flow

Experimental observations of the motion of ellipsoids in a rotating horizontal drum, fully filled with very viscous fluid, have been recorded. For a given drum speed an ellipsoid lies adjacent to the rising drum wall at a fixed position, with its long axis $a$ parallel to the direction of wall motion. For ellipsoids with maximum radius of curvature less than that of the drum wall, the positions at which they lie appears to be independent of $a$. Ellipsoids with maximum radius of curvature greater than that of the drum wall tilt with respect to the direction of drum motion and then undergo lateral translations from end to end of the drum.