Role of streaming potential on magneto-couple-stress fluid flow and heat transfer in a rotating microfluidic channel

We investigate the streaming potential, which is an electrokinetic coupling between couple stress fluid flow and electric potential, to understand the efficient performance of an electrokinetic system in the presence of an external magnetic field. The streaming potential is used to determine the energy conversion efficiency with electroosmotic mobility in a rotating microchannel. The model includes the solution of the Poisson–Boltzmann equation, a non-Newtonian couple stress fluid model, and thermal energy equations with Joule heating effects. We derive analytical expressions for streaming potential and temperature distribution in a rotating microchannel with vanishing couple stress and no-slip at the walls. The analysis shows that axial velocity profiles adopt a parabolic form under low rotational effects, with peak velocities increasing alongside the couple stress parameter due to reduced microstructural resistance. The imposed magnetic field suppresses flow through Lorentz force damping, whereas rotational effects enhance transverse velocity components via Coriolis-driven secondary flows. The axial component of streaming potential intensifies with thicker electric double layers, while both rotation and couple stress effects strengthen the transverse component. Thermal transport is significantly influenced by viscous dissipation and Joule heating, with an increased couple stress parameter promoting heat accumulation, while rotation and magnetic fields enhance convective cooling. The streaming potentials indicate that energy conversion efficiency improves with the couple stress parameter but deteriorates under stronger magnetic inhibition. These results highlight the intricate coupling among electrokinetic phenomena, Coriolis force, magnetic interactions, and non-Newtonian fluid microstructure, providing important insights for enhancing microscale flow control and energy harvesting applications.