Mixed convection of rotating nanofluid in vented corrugated enclosures: Thermal performance and porous media implications

Flows confined within enclosures containing rotating objects are of significant practical importance in various engineering and industrial applications. These include centrifugally-driven separation processes, electrochemical cells, chemical reactors, tribology, oil and gas production, hydraulic equipment, and fluid viscometers. Understanding the mixed convective flow in an enclosure with sinusoidal horizontal walls and a rotating cylinder in a vertically-oriented annular gap, where the outer wall is stationary and the inner wall rotates, is crucial within the broader scope of fluid dynamics. This study analyzes the forced convection of a copper oxide nanofluid in a porous parallelogram cavity with inlet and outlet ports. The flow and thermal distributions are influenced by the porous media and the copper oxide nanoparticles. Forced convection within the enclosure is induced by the inflow of external cold fluid and the rotation of the cylinder. A partially heated corrugated wall at the bottom of the cavity facilitates free convection, while the upper corrugated wall is kept cold, and the remaining walls are insulated. This physical model is converted into a set of partial differential equations, which are solved using the finite element method. The results are presented in terms of the Nusselt number, line graphs, and contour maps. The outcomes indicate that increasing the nanoparticles concentration from 0 to 0.2 enhances the Nusselt number by up to 21 times compared to the based fluid. While the skin-friction coefficient along the rotating cylinder exhibits alternating positive and negative values due to rotation-induced flow reversal. This oscillation becomes stronger as the rotation speed increases.