Multiscale numerical modeling of heat transfer enhancement in a magnetized porous cavity filled with CuO–Ag–Al2O3/water ternary nanofluid

The present study numerically investigates natural convection heat transfer of a CuO–Ag–Al₂O₃/ water ternary hybrid nanofluid in a porous cavity containing a centrally located isothermal solid block under a magnetic field. Equal proportions of the three nanoparticles are considered. The governing equations are discretized using the finite volume method (FVM), with the SIMPLE algorithm employed for pressure–velocity coupling. The numerical model is validated against previously published results. Flow and thermal characteristics are analyzed using streamlines and isotherms, while heat transfer performance is quantified using the average Nusselt number. The results show that the average Nusselt number increases with increasing Rayleigh number (Ra), Darcy number (Da), and nanoparticle volume fraction (ϕ), but decreases with increasing Hartmann number (Ha). Increasing the nanoparticle volume fraction from 0 to 0.04 enhances heat transfer, with the maximum relative enhancements of 12.31% at Ra= 10 3 , 1.17% at Ha= 0, and 10.83% at Da= 10 −5 . The originality of this study lies in the combined investigation of nanoparticle loading, porous-medium permeability, and magnetic-field effects on natural convection in a porous cavity with a centrally located isothermal blockage. The findings provide insights into the potential use of ternary hybrid nanofluids for thermal management applications where heat transfer enhancement and magnetic flow control are important.