Deformation Fields and Residence Time Distributions in Polymer Melt Flows

In past numerical simulations of polymer melt flows, the flow field has been visualized through velocity vectors and streamlines providing a steady-state Eulerian viewpoint. This work shows that enhanced understanding of flow kinematics can be achieved by calculating the residence time distribution (RTD) of material points through the integration of the known velocity field and by plotting isochrones and the deformation field of fluid elements. Such kinematic patterns provide a Lagrangian viewpoint of the flow and fully describe the history of the elements of the system as they move through the field. In cases with zones of recirculation the period for one revolution is also calculated. Typical examples are shown for such polmyer processing operations as entry flows in contractions, exit flows from dies, calendering and wire-coating coextrusion processes.