The flow of a FENE-fluid through a 4:1:4 constriction in a tube is computed by a split Lagrangian-Eulerian finite element method. In steady flow it is found that the upstream vortex grows with increasing Deborah number, while the downstream vortex diminishes and disappears. The steady pressure drop decreases with Deborah number unless the finite extensibility $L$ is quite small. Starting from rest at high Deborah number, the upstream vortex grows in two stages, each with their own time scales. A simple model of this growth is proposed.
|Journal||J. Non-Newtonian Fluid Mech.|
|Publication status||Published - 1997|