(296c) Taylor-Couette Flow Behavior with Polyelectrolyte Solutions

Taylor-Couette (TC) flow, which is flow between two concentric, rotating cylinders, is ideal for studying flow behavior of complex solutions due to the wide variation of hydrodynamic flow states available. The addition of non-Newtonian polymer solutions increases the elasticity of the solution, which in turn can modify flow states that are typically dominated by inertial forces. Prior studies have used nonionic polymers, such as polyethylene oxide, to examine the role of elasticity in TC flow. In this study, a cationic polyacrylamide was used to modify the elasticity of the solution, and varying concentrations of NaCl were added to alter the ionic strength of the solution. The coil conformation of charged polymers changes depending on the ionic strength, from a more rigid conformation at low ionic strengths to a more flexible conformation at high ionic strengths, resulting in different non-Newtonian responses of the fluid to shear. The effect of polymer conformation as a result of varying solution ionic strength on TC flows from Taylor Vortex Flow to Turbulent Taylor Vortices with co- and counter-rotation of the cylinders will be discussed. The talk will end with implications for the use of TC hydrodynamics for tuning polymer-particle assemblies in flow.