Fluid Dynamics of Dissolved Polymer Molecules in Confined Geometries

The past decade has seen a renaissance in the study of polymer solutions flowing in confined geometries, the renaissance driven in part by advances in visualization of large DNA molecules and the desire to manipulate DNA for genomic applications. This article summarizes the features of the fundamental polymer physics and fluid dynamics that are relevant to the flow of confined polymer solutions, then reviews the recent literature on the topic. Experiments have clarified and extended prior work showing that diffusion of confined flexible polymers is substantially altered by confinement and that, during flow, polymers exhibit substantial cross-stream migration. Simulation methods have been developed that have the capability of capturing both polymer and fluid motion in confined geometries and yield results that are in semiquantitative agreement with experiments in dilute solutions. Kinetic-theory treatments of simple polymer models have led to analytically tractable models that qualitatively encompass the key phenomena observed in experiment.