Entropy generation and streaming potential in magneto–electrokinetic couple stress flow through rotating porous microchannels

Abstract

We investigate the entropy generation and streaming potential in the electroosmotic flow of a couple stress fluid through a slowly varying rotating microchannel. We examine the influence of an external magnetic field, porous permeability, and the Coriolis force on flow characteristics and entropy generation. The study employs a combination of semi-analytical and finite difference numerical methods to solve the governing equations associated with the current model. We present graphical analyses of velocity and temperature distributions, entropy generation, and Bejan number profiles to evaluate irreversibility and heat transfer rates. Furthermore, this study estimates the electrokinetic energy conversion efficiency from electrical double layer (EDL) ions to power generation. The electrokinetic energy conversion improves when the EDL is thicker, the porous medium has higher permeability, and the rotational speed increases. Conversely, the magnetic field reduces energy conversion. Higher values of the couple stress parameter and porous parameter contribute to increasing the Bejan number, whereas the Joule heating and the magnetic field have a reversal effect. The axial streaming potential rises with greater electroosmotic parameters and rotation speeds. These findings enhance understanding of the thermodynamic behavior of couple stress fluids in various engineering applications, such as electroosmotic flow in microchannels and porous media.