Hydrodynamics in media with migrating macromolucules: development of FDCF asymptote

Abstract

A detailed investigation of the hydrodynamical changes occurring due to polymer migration in non-homogeneous flows of macromolecular solutions is presented. The governing equaitons formulated by Cohen have been modified and numerically solved for infinitely long capillaries. The resulting fully-developed concentration field (FDCF) asymptote is shown to provide an upper bound on the flow enhancement obtainable in flows with migrating macromolecules. Comparison of the numerical predictions with the experimental data lend support to the norion that the phenomenon of polymer migration actually occurs by a slow diffusive process and not, perhaps, by a rapid instability mechanism invoked by Jansen. A number of observations of engineering interest have been deduced and key experiments suggested that may throw more light on the intriguing migration phenomena, which defy a totally satisfactory explanaiton to date.