(283b) Stress-Gradient-Induced Polymer Migration in Microfluidics

We develop a continuum theory for the stress-gradient-induced migration of polymers in presence of solid boundaries and apply this to a model electro-osmotic flow with periodic slip wall velocity. We obtain theoretical results for the steady-state distribution of dilute polymer solutions using a systematic perturbation analysis in Weissenberg number. The theory is also extended to incorporate additional effects due to wall hydrodynamic interactions. By comparing the theoretical results with Brownian Dynamics (BD) and Stochastic Rotation Dynamics (SRD) simulations, we show that our theory can accurately capture the migration phenomena when the polymer coil size is less than half of the length scale over which the velocity gradient changes. Predicting polymer distribution in confined geometries is crucial in lubrication, oil recovery, microelectronics processing, and next generation DNA sequencing technologies.