Natural convection heat transfer of water/Ag nanofluid inside an elliptical enclosure with different attack angles Seyed Alireza Rozati, Farnaz Montazerifar, Omid Ali Akbari, Siamak Hoseinzadeh, Vahid Nikkhah, et al. Mathematical Methods in the Applied Sciences, 2026 In this presentation, flow physics and natural heat transfer of water/Ag nanofluid are implemented by utilizing finite volume method (FVM) considering 0–6% of solid nanoparticles in volume fraction in an elliptical‐shaped enclosure affected by different attack angles range from 45° to 135°. This survey's foremost objective is to find the optimum attack angle for the highest heat transfer performance in the studied geometry. The attained results demonstrated that the Rayleigh number's augmentation leads to buoyancy force amplification and intensification of velocity components in the enclosure. Hence, the shapes of streamlines for each attack angle are different from the other states. The enhancement of the Rayleigh number causes better temperature distribution between cold and hot sources. The attack angle changes are the other factor for creating and intensity of the temperature gradients. By increasing the attack angle when the heat is transferred from the hot source to the top of the enclosure, the thermal distribution effects come with high gradients due to the flow balance disturbance and the changes in two sources' location. As the fluid moves, velocity components always change. In Rayleigh number of Ra = 1 × 10 3 due to a decrease of buoyancy force and negligible density changes in the enclosure, the average friction coefficient (C fave ) is not considerable, and for everyone studied attack angles, these changes are negligible. By augmenting attack angle (attack angles of 90° and 135°), because the tangential velocity component is weakened by gravity force, the values of created surface stress and fluid adhesion to the hot surface are less.
