Finite-Element simulation of the start-up problem for a viscoelastic fluid in an eccentric rotating cylinder geometry using a third-order upwind scheme

We numerically simulate the flow field of a dilute polymeric solution using a finitely extendable nonlinear elastic (FENE) dumbbell model. A third-order accurate finite element upwind scheme is used to discretize the convection term in the FENE dumbbell equations for the configuration tensor. The numerical scheme also avoids unphysical negative values for diagonal components of the configuration tensor. The FENE dumbbell equations are solved along with the momentum and continuity equations at small Reynolds numbers with an accuracy of second order in time. In this work we apply this numerical technique to the motion of a viscoelastic fluid in an eccentric rotating cylinder geometry. We obtain the velocity and the polymer contribution to the stress fields as a function of time, and also examine the steady solutions. A particular focus is the influence of coupling between changes in polymer conformation and changes in the flow that occurs as the polymer concentration is increased to a level where the polymer contribution to the zero-shear viscosity of the solution is equal to that of the solvent.This research was supported under grants from the National Science Foundation and the San Diego Supercomputer Center.