ABSTRACT: Both numerical and experimental investigations were conducted to study the thermal and flow behavior via natural convection between two vertical walls with a triangular heated cylinder and three staggered plates. The experimental setup featured two vertical adiabatic walls with an aspect ratio of A = 12. Air flowed in from the bottom and exited from the top, which was open to the atmosphere. A horizontally heated triangular cylinder, with a side length of 26 cm, was subjected to constant heat fluxes of 200 W/m², 400 W/m², and 800 W/m². The configurations tested included setups without staggered plates (h = 0.0 cm) and with plates of varying lengths (h = 0.5, 1.0, 1.5, and 2.0 cm) attached to the cavity walls. Numerical simulations were performed using ANSYS FLUENT 2020 to solve the governing equations. The results indicated that the Nusselt number increased with higher Rayleigh numbers, greater heat fluxes, smaller inclination angles, and larger lower surface opening distances. Additionally, incorporating fins of any geometry enhanced the rate of heat transfer. The optimal enhancement in the Nusselt number occurred with ribs, showing increases of 7%, 15%, 38%, and 42% for the cases of h = 0.0 cm, and h = 0.5, 1.0, 1.5, and 2.0 cm, respectively. The experimental data were compared with the numerical results, showing good agreement under identical conditions.