Natural Convective Flow Inside a Confined Enclosure Filled with Hybrid Nanofluid: Finite Volume Method

LS2ME polydisciplinary faculty of Khouribga, Sultan Moulay Slimane University BP: 145 25000, Morocco.

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Published online: 22 May 2026

Abstract

This work investigates heat transfer enhancement using natural convection in a square cavity filled with Cu-Ag/water (75:25) and Cu-Au/water (75:25) hybrid nanofluids. The physical model and governing equations including continuity, momentum, and energy are formulated and solved using the finite volume method (FVM). The analysis explores different conditions, including Rayleigh numbers ranging from 10³ to 10⁵, which correspond to weak to strong convection, and nanoparticle volume fractions between 0.01 and 0.03. These parameters are studied to understand their impact on heat transfer performance. The results show that adding nanoparticles clearly improves convective heat transfer. The average Nusselt number increases as the nanoparticle concentration rises, and this effect becomes even more pronounced at higher Rayleigh numbers due to stronger buoyancy-driven flow. It is also observed that the Cu-Ag hybrid nanofluid performs slightly better than the Cu-Au one. Overall, these findings suggest that hybrid nanofluids can be an effective solution for enhancing natural convection, with potential applications in areas such as electronics cooling, solar energy systems, and heat exchangers.