Thermal analysis of Al₂O₃-water nanofluid within a ribbed enclosure

This study investigates natural convection heat transfer in a ribbed annular cylinder filled with pure water and Al₂O₃ nanoparticles. The natural convective heat transfer is numerically simulated, considering variable viscosity and thermal conductivity of the Al₂O₃-water nanofluid. The flow field and temperature distribution are analyzed by evaluating the effects of volume fraction and Rayleigh number. Typically, Al₂O₃ nanoparticles significantly influence the Nusselt number, enhancing both the thermal conductivity and viscosity of the fluid. It is observed that for nanoparticle volume fractions of 7%-9%, the effect of volume fraction on heat transfer is minimal in an annulus cylinder without ribs. Heat transfer in the nanofluid improves as the Rayleigh number increases, and the presence of ribs causes a shift in heat transfer enhancement from the upper to the lower region.