Lagrangian Topology of Reoriented Potential Flows

摘要

Scalar transport in closed potential flows is investigated for the specific case of a periodically reoriented dipole flow. For scalar advection, Lagrangian chaos can be achieved with breakdown of the regular Hamiltonian structure, which is governed by symmetry conditions imposed by the dipole flow. Instability envelopes associated with period-doubling bifurcations of fixed points govern which regions of the flow control parameter space admits global chaos. These are further refined via calculation of Lyapunov exponents. These results suggest significant scalar transport enhancement is possible within potential flows, given appropriate programming of stirring protocols.