Finite element analysis of natural convection and entropy generation in a T-shaped cavity with an octagonal block

Natural convective heat transfer (NCHT) supports various technologies in geophysics, and biomedicine. Entropy generation (EG) results in efficiency, cost, and emissions implications for thermal systems. NCHT with EG in closed T-shaped cavities with obstructions has not been explored in depth; there are no systematic EG maps, few FEM benchmarks, and little is known about the trade-off between geometry and performance. To this end, we conducted an FEM to model steady, laminar flow, heat transfer, and EG in a T-shaped cavity with an octagonal block. For the Ra, increasing 10³−10⁶, the convection strength sharply increases; the maximum Nusselt number increases approximately 366%, the peak velocity increases approximately 24,581% and the wall heat transfer increases approximately 19,436%. Meanwhile, the Bejan number goes from ~1 to < 0.2, indicating irreversibility due to friction is significant at peak Ra. The contributions from this analysis can inform industries ranging from compact heat exchangers and electronics cooling to passive thermal systems.