CHAOTIC ROTATION OF TRIAXIAL ELLIPSOIDS IN SIMPLE SHEAR-FLOW

Chaotic behaviour is found for sufficiently long triaxial ellipsoidal non-Brownian particles immersed in steady simple shear flow of a Newto nian fluid in an inertialess approximation. The result is first determ ined via numerical simulations. An analytic theory explaining the onse t of chaotic rotation is then proposed. The chaotic rotation coexists with periodic and quasi-periodic motions. Quasi-periodic motions are d epicted by regular closed loops and islands in the system Poincare map , whereas chaotic rotations form a stochastic layer.