Computational Analysis of Heat Transfer Enhancement in a Trapezoidal Cavity with Central Circular Obstacle

This study numerically explores natural convection in a trapezoidal enclosure with a wavy upper boundary and a centrally placed circular cavity of varying radius. The left vertical wall is maintained at a low temperature, while the right wall is heated. The remaining boundaries are adiabatic. Three obstacle sizes are considered with radius 0.05, 0.08 and 0.03 representing different levels of geometric blockage. Simulations are carried out in COMSOL Multiphysics for Rayleigh numbers between 10<sup>3</sup> and 10<sup>6</sup> under the Boussinesq approximation. Flow circulation temperature contours and heat transfer performance are analyzed for each configuration. The results indicate that enlarging the circular cavity alters the strength and structure of buoyancy-driven vortices, influencing thermal stratification and the effective heat transfer rate across the cavity. At low Rayleigh numbers conduction dominates and influence of cavity size limited whereas at higher Rayleigh numbers natural convection becomes significant and the obstacle radius strongly affects vortex dynamics and Nusselt number distribution. The findings provide insight into the coupled effect of cavity geometry and buoyancy intensity offering guidance for the design of thermal system with internal obstacles and irregular enclosures. The main objective of this paper is to find out the effect of natural convection of air within a wavy chamber using finite element methods and to investigate the influence of heated wall on free convection flow numerically.