Impact of discontinuous deformation upon the rate of chaotic mixing.

Mixing in smoothly deforming systems is achieved by repeated stretching and folding of material, and has been widely studied. However, for the classes of materials that also admit discontinuous deformation, the theory of mixing based on the assumption of smooth deformation does not apply. Discontinuous deformation provides additional topological freedom for material transport and results in different Lagrangian coherent structures forbidden in smoothly deforming systems. We uncover the impact of discontinuous deformation on mixing rates, showing that mixing can be either enhanced or impeded depending on the local stability of the underlying smooth map.