Numerical investigation of mixed convection heat transfer enhancement in a square cavity with a hump-shaped heated bottom wall

■ Mixed convection was analyzed in a cavity with a heated hump-shaped bottom wall. ■ Effects of Reynolds, Grashof, and Prandtl numbers were systematically investigated. ■ Buoyancy effects were found to enhance vortex formation and thermal mixing. ■ Shear-driven flow was shown to dominate at high Reynolds numbers, suppressing buoyancy. ■ Geometric modification was demonstrated to significantly improve thermal efficiency. Mixed convection heat transfer in enclosures is critical for many engineering applications, yet the influence of bottom-wall geometric modifications remains insufficiently explored. This study numerically investigates the thermo-fluid behavior in a lid-driven square cavity incorporating a centrally positioned hump on the uniformly heated bottom wall. The coupled Navier–Stokes and energy equations are solved using the Galerkin finite element method within COMSOL Multiphysics for Reynolds numbers ( 1 ≤ Re ≤ 100 ), Grashof numbers ( 10³ ≤ Gr ≤ 10⁵ ), and Prandtl numbers ( 0.015 ≤ Pr ≤ 10 ). Results show that increasing Gr enhances buoyancy-driven convection, establishing secondary vortices and stronger thermal gradients, while higher Re enhances shear-driven flow that can suppress natural convection. The Prandtl number strongly influences heat transfer, with low Pr exhibiting smooth thermal fields and high Pr yielding sharper gradients. The hump-shaped geometry promotes localized circulation and enhances thermal mixing, increasing the average Nusselt number ( Nu ) by up to 45% compared to a flat-bottom cavity at Re = 100 and Gr = 10⁵ . These results emphasize the potential of geometric tailoring to enhance convective heat transfer in applications such as electronics cooling, energy storage, and HVAC system design.