Rotating electroosmotic flow through a polyelectrolyte-grafted microchannel: An analytical solution

Abstract

We investigate the flow dynamics of an incompressible fluid in a polyelectrolyte grafted rotating narrow fluidic channel under the influence of an externally applied electric field. Here, we invoke an analytical formalism to solve the transport equations governing the flow dynamics in the rotating environment. We bring out the rotational force driven complex flow dynamics in the channel as modulated by the soft layer induced alteration in the electrostatic potential under electrokinetic actuation. We observe that the flow reverses at the centre of the channel for higher rotational speeds, emerging from an intricate competition among the rotation induced Coriolis force and the electrical body force due to the electrical double layer phenomenon. We show that an increase in the thickness of the polyelectrolyte layer (PEL) increases the transverse electrostatic potential, which upon interacting with the externally applied electric field alters the flow dynamics non-trivially in a rotating platform. Furthermore, we show that the frictional drag, stemming from the presence of ions in polymeric chains in the PEL enhances the resistance to the flow field, leading to a reduction in flow velocities in the channel. Finally, we explain the consequential effects of grafted PEL as realized through the thickness of the layer and the PEL drag on the alteration in the volume transport rates in the channel.