Effect of streaming current on helical flows of power law fluids

Abstract

We highlight the implications of electrokinetic effects on the axially pressure driven flow of a shear-thinning fluid in the gap between two concentric cylinders rotating with a relative angular velocity. Such helical flows are important from a practical perspective, as these may lead to a non-trivial alteration in the axial volume flow rate, owing to a combined interplay of the kinematics, electro-hydrodynamics, and the flow rheology. In particular, our results demonstrate the consequences of the establishment of an induced electrical potential, also known as streaming potential, on the volumetric transport, for shear thinning fluids. Our results demonstrate that an increment in the relative rotational speed induces more electrokinetic resistance into the flow. The flow rate initially decreases with increment in the relative angular speed till it reaches a minima for a given power law index, beyond which it again increases. The analytical and numerical results presented in this work bear significant consequences in the design of novel microfluidic systems governed by electrokinetic effects.