Abstract Natural convection in enclosed cavities is a key phenomenon in many engineering applications such as electronic cooling systems, heat exchangers, solar energy collectors, thermal storage units, an‎d HVAC equipment. The use of nanofluids has emerged as an effective approach to enhance heat transfer performance in such systems. Therefore, investigating the thermal behavior of nanofluids in inclined cavities can significantly contribute to the design an‎d improvement of thermal equipment. In this study, natural convection of a nanofluid inside an inclined square cavity is numerically investigated using ANSYS Fluent. The main objective is to analyze the effects of inclination angle, Rayleigh number, an‎d nanoparticle concentration on temperature distribution, flow structure, an‎d heat transfer rate. Simulations are carried out for three inclination angles (0∘,30∘,60∘), three Rayleigh numbers (104,105,106), an‎d three nanoparticle concentrations (0%,2%,4%). The results show that the inclination angle has a significant influence on the flow field an‎d heat transfer. The angle of 30 degrees produces the highest Nusselt number due to better alignment of buoyancy forces an‎d enhanced flow circulation. The investigation of nanoparticle concentration reveals that adding an optimal number of nanoparticles improves heat transfer, with 2% concentration providing the best performance. Higher concentrations such as 4% lead to increased viscosity an‎d reduced flow strength, resulting in a slight decrease in heat transfer. Furthermore, increasing the Rayleigh number strengthens natural convection an‎d substantially increases the Nusselt number. Comparison between the base fluid an‎d the nanofluid indicates that the nanofluid enhances heat transfer by approximately 6–9%. Overall, the findings demonstrate that selec‎ting an appropriate cavity inclination angle an‎d an optimal nanoparticle concentration plays a key role in improving the thermal performance of natural convection systems an‎d contributes to the optimal design of advanced thermal equipment.

مرضيه رضازاده

هادي صفائي , حامد رضوي بني