Single ellipsoid in simple shear flow: influence of inertia

Authors: Rosén, T., Kotsubo, , Do-Quang, M., Aidun, C. K., Lundell, F.
Document Type: Conference
Pubstate: Published
Journal: 9th International Conference on Multiphase Flow (ICMF), Firenze, Italy (2016)
Year: 2016


The orientational dynamics of non-spherical particles in fluid flows depends on their reaction to local velocity gradients. For macroscopic particles, the velocity gradients can be strong enough for inertial effects to influence the results. To get fundamental understanding of the evolution of the orientational distribution of suspended particles due to inertia, we consider the behavior of one single ellipsoidal particle in simple shear flow. The case of a single spheroidal particle (an ellipsoidal particle with rotational symmetry) has been studied extensively in the recent years both theoretically and numerically. Less focus has been given to the tri-axial ellipsoidal particle, which will therefore be the main focus of this work. In the absence of inertia, it is well known that the nearly prolate tri-axial ellipsoid can perform chaotic orbits in shear flow. It has also previously been seen that this chaotic motion is inhibited by sufficient particle inertia, which promotes a drift towards rotation around the minor axis. In this work, we find that fluid inertia is an even stronger inhibitor of chaos and that the rotation around the middle axis stabilizes even at low particle Reynolds numbers. At moderate Reynolds numbers, the nearly prolate tri-axial ellipsoid actually behaves similarly to the perfectly prolate one. Thus, slight tri-axiality of the prolate spheroid does not induce fundamental changes of the dynamics (from predictive to chaotic) if fluid inertial effects are present.