Dumb-bell model for polymer transport in laminar flows

Polymer transport is investigated for two paradigmatic laminar flows having open and closed streamlines, respectively. For both types of flows we find transport depletion owing to the action of the polymers elastic degree of freedom. For flows with closed streamlines the leading mechanism for the observed transport reduction is the (dynamical) formation of barriers. For flows with open streamlines the reduction of transport is induced by the renormalization of the bare diffusion coefficient. Results have been obtained by means of Lagrangian simulations.