<p>This study explores a natural convection model in a cavity placed horizontally with fins. The traditional continuous fin geometry is replaced by a staggered type. The effects of fin height, spacing, thickness, and arrangement are investigated. Firstly, the inverse method is used to estimate the actual heat transfer rate in the experiment and discuss the turbulence model suitable for the experimental model. After that, the direct method is used to study the impact of different geometric parameters and arrangements on the natural convection heat transfer of the staggered fins placed horizontally in the cavity. The built-in function is used to obtain the temperature field and velocity field and then calculate the average Nusselt number and equivalent thermal resistance for comprehensive analysis. The inverse solutions show that the RNG k-ε model is the most suitable among the three turbulence models. The direct solution results show that increasing the fin height reduces the average Nusselt number, but expands the heat transfer area and improves the thermal performance. In addition, increasing the fin spacing enhances the natural convection effect between fin channels, thus improving thermal performance. Although expanding the fin thickness can increase the heat dissipation effect, it is not as significant as increasing the fin height. Finally, the staggered fin arrangement can promote fluid convection and reduce the thickness of the thermal boundary layer, thereby improving thermal performance.</p>