Natural convection in a 3D trapezoidal cavity with nanofluid and internal cylinders

This work considered the natural convection in a 3D trapezoidal cavity filled with Al₂O₃-water nanofluid. The left and right vertical cavity walls were maintained at different hot and cold temperatures. We compared the results of the considered tests to those of pure water and evaluated the effect of the solid volume fraction at two different values. The examined range of Rayleigh number was 10³ ≤ Ra ≤ 10⁶. In three considered cases, the insertion of a cylindrical body into a cavity was also explored. The cylinder’s radius of the first case is 0.15 times the length of the cavity. The remaining situations were two vertically aligned cylinders, and their radius was 7.5% of the cavity side length. The findings indicate that a higher solid volume fraction improves the average Nu, and this improvement increases with Ra. For the inner cylinder cases with double cylinders above single cylinders, the average Nuwas increased. On the other hand, the cylinders’ misaligned location improves more than in any other case. Also, when the locations of the cylinders varied at the maximum horizontal or vertical velocities, it was determined that Ra had no influence.