Breaking time reversal symmetry by viscous dephasing -: art. no. 037301

We show that in generic situations a reversible periodic driving of a Stokes flow will not result in a reversible flow field. Each eigenmode of the Stokes operator responds with a phase delay that depends on frequency and damping, resulting in a viscous dephasing that destroys time reversal symmetry and hence prepares for chaotic advection. The general theory is illustrated for a two-dimensional vortex pattern that can be generated in current driven flows in a magnetic field.