Chaotic advection in a cavity flow with rigid particles

The effect of freely suspended rigid particles on chaotic materialtransport in a two-dimensional cavity flow is studied. We concentrateon the understanding of the mechanism how the presence of a particleaffects the dynamical system of the flow. In contrast to the casestudied by Vikhansky [A. Vikhansky, Phys. Fluids, vol.15 (2003) 1830],we show that even a regular periodic motion of a single particle caninduce chaotic advection around the particle, as a result of theperturbation of the flow introduced by the freely rotating solidparticle. This perturbation is of a hyperbolic nature. In fact,stretching and folding of the fluid elements are guaranteed by theoccurrence of the hyperbolic flow perturbation centered at theparticle and by the rotation of the freely suspended particle,respectively. The fluid-solid flow problem has been solved by afictitious-domain/finite-element method based on a rigid-ringdescription of the solid particle. A single-particle system isstudied in detail in view of the dynamical systems theory and thenextended to two- and three-particle systems