Blinking rolls: Chaotic Advection in a 3D Flow with an Invariant

Paul Mullowney, Keith Julien and James Meiss

University of Colorado

Chaotic advection of passive scalars can act as an efficient mixing method even when the underlying flow is not turbulent. Here, we discuss a 3D analog of the 2D blinking vortex model of Aref that exhibits complex and chaotic behavior. The fluid motion consists of alternately active 2D rolls acting in different planes. For our system, as in Aref's case, exact solutions of the particle trajectories can be used to explicitly construct a mapping for the system. We will show that when the rolls are orthogonal there is an invariant that prevents full mixing, though two-dimensional mixing occurs. We vary the parameters of the system and study the efficiency of the resulting mixing.