Nonaxisymmetric high-aspect-ratio ellipsoids under shear: Lowest-order correction for finite aspect ratios

We extend the classic study of the motion of small ellipsoidal particles under shear, focusing on simplifications obtained by considerations of the extreme aspect ratios typical of rheoscopic particles (e.g., Kalliroscope). Specifically, we study conditions under which the long-time behavior of scalene (i.e., triaxial or nonaxisymmetric) ellipsoids are well approximated by a model that is low order in the appropriate aspect ratios. After enumerating and describing the generic long-time motions of such particles in the lowest-order model, we investigate corrections induced by the physically appropriate lowest-order correction to the base model, with special attention to a periodic wobbling motion special to scalene ellipsoids.