Heat transfer analysis of electroosmotic flow of couple stress fluid through a rotating circular microchannel

Abstract

The present study explores the flow and heat transfer characteristics of couple stress fluid through a rotating circular microchannel under the influence of electromagnetic fields. This analysis considers the angular and axial flows to be actuated by a pressure gradient, electromagnetic force, and rotation of the circular microtube. Initially, the Debye-Hückel approximation is utilized to get an analytical solution of the Poisson-Boltzmann equation for the electric potential within the electric double layer. Next, field equations for couple stress fluid are introduced with two types of boundary conditions, namely Type A (i.e., vanishing of couple stresses) and Type B (i.e., super adherence condition), which were proposed by V.K. Stokes. Then, the solutions are obtained for each case. Subsequently, these solutions are utilized to solve energy equation by employing the finite difference technique with the aid of the Thomas algorithm. It is perceived that the couple stress parameter enhances the axial velocity but retards the angular velocity, whereas the magnetic field parameter diminishes axial velocity and elevates angular velocity. This study examines the impact of the rotational parameter on angular velocity. Furthermore, the magnitude of temperature rises with both couple stress parameters and the Brinkman number, but it drops with the Hartmann number. In addition, an extensive study on Nusselt number, a significant dimensionless heat transfer parameter, is conducted. Overall, Type A condition has a greater impact on velocity and temperature than Type B condition. The current model may be used as a novel approach to manipulate fluid flow at the microscale for designing microfluidic devices such as microdrillers, micromixers, and microreactors, with potential applications in chemical mixing and processing, blood plasma separation, nanoparticle synthesis, drug delivery and screening systems, and drug mixing.