We examine the transport properties of a particular two-dimensional, in viscid
incompressible flow using dynamical systems techniques. The velocity field is time
periodic and consists of the field induced by a vortex pair plus an oscillating strain-
rate field. In the absence of the strain-rate field the vortex pair moves with a constant
velocity and carries with it a constant body of fluid. When the strain-rate field is
added the picture changes dramatically; fluid is entrained and detrained from the
neighbourhood of the vortices and chaotic particle motion occurs. We investigate the
mechanism for this phenomenon and study the transport and mixing of fluid in this
flow. Our work consists of both numerical and analytical studies. The analytical