Natural convective flow of CuO–Water nanofluid with variable thermophysical properties in a square-shaped cavity with an obstacle

Abstract The current study involves numerical simulation to analyze the effect of magnetohydrodynamic (MHD) forces on natural convection within a square enclosure containing an inner corrugated circular cylinder. Additionally, the effect of nonlinear thermal radiation is considered. In this model, the nanofluid composed of copper oxide (CuO) and water is diffused all throughout the porous medium of the enclosure. It is considered that the nanofluid's temperature and nanoparticle volume concentration both affect the dynamic viscosity and thermal conductivity. The outer square-shaped enclosure is supposed to be cold, while the inner corrugated cylinder is presumed hot. Flow and thermal patterns inside the enclosure are visualized through the distribution of streamlines and isothermal contours. Heat transfer rates are estimated based on the local (NuL) and average (Nuavg) Nusselt number. Computational results are generated for several parameters, including Rayleigh number (Ra), Darcy number (Da), Hartmann number (Ha), surface temperature parameter (χ), radiation parameter (Rd), and solid volume concentration of nanoparticles (ϕ). The fluid flow intensity is noticeably improved by increasing the Rayleigh number, radiation, surface temperature, and concentration of nanoparticles, but an increasing Hartmann number counteracts this phenomenon. The heat transfer rate throughout the enclosure can be significantly reduced by filling it with a porous substance.