Unsteady flows of micropolar fluids parallel to the axis of an annular domain with a porous layer

Transient flows of micropolar fluids through circular domains are investigated. The flow domain has two annular regions. The outer region is clean, while the inner region contains a porous medium. The analytical solutions in closed forms for the linear and angular velocities in both regions are determined using the Laplace transform and finite Hankel integral transform under the assumptions of the continuity of the velocities, stresses, and couple stresses on the interface. The obtained solutions are new in the literature and can generate solutions for some particular cases of filtration processes involving polymeric fluids with additives or other fluids that show similarities to micropolar fluids. Effects of various parameters on the fluid motion have been investigated by numerical simulations and graphical illustrations.& COPY; 2023 THE AUTHORS. Published by Elsevier BV on behalf of Faculty of Engineering, Alexandria University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).

Automated summary

This study investigates the transient flows of micropolar fluids through circular domains. The flow domain consists of two annular regions, with the outer region being clean and the inner region containing a porous medium. Analytical solutions for the linear and angular velocities in both regions, obtained using Laplace transform and finite Hankel integral transform, are determined under the assumption of continuity of velocities, stresses, and couple stresses on the interface. The obtained solutions are novel and can provide solutions for specific cases of filtration processes involving fluids with similarities to micropolar fluids. Numerical simulations and graphical illustrations are used to investigate the effects of various parameters on the fluid motion.