Flávio Medeiros Seibt

Constructal Design of a Triangular Fin Inserted in a Cavity with Mixed Convection Lid-Driven Flow

The present work applies Constructal Design to study numerically a fin-cavity system under mixed convection flow. The system is composed of a heat triangular fin inserted in a squared cavity. The flow is driven by the superior wall (lid) displacement. The main purpose is to study the effect of the fin geometry and area ratio (φ) over the dimensionless convective heat transfer coefficient (Nusselt number). The effect of Rayleigh (RaH) and Reynolds (ReH) numbers over the thermal performance and optimal geometries is also evaluated. For all cases the Prandtl number is constant (Pr = 0.71). The conservation equations of mass, momentum and energy are solved numerically with a code based in the Finite Volume Method (FVM). Results showed that the thermal performance increased with the increase of Reynolds and Rayleigh numbers and with the decrease of fin area ratio (φ). Otimal geometries for the triangular fin are compared to optimal rectangular fins, for RaH = 105 results showed a better performance (up to 8%) of the triangular fin for low Reynolds numbers (ReH < 200), while rectangular fins performed better than triangular ones for the highest magnitudes of ReH numbers. In general, results showed that different conditions change the optimal shape of a flow system, always evolving to architectures that facilitate the access to the flows that flow through it.