Abstract
The present work exhaustively examines natural convection in complex enclosure forms such as trapezoidal, rhombic (parallelogrammic), elliptical and wavy geometries, taking into account various numerical methods that have been used in previous studies over the last ten years. Many dimensionless parameters such as a wide range of dimensionless numbers like Rayleigh, Darcy, and Hartmann were treated. The influence of the volume fraction of nanofluids, the thickness of the porous layer, and the number of undulations are studied. The existence of an inner body with different shapes (square, rectangle, triangle, rhombic, elliptical and wavy) was also mentioned. The impact of the position of the inner body and its size were also examined. The results of the previous works are presented in term of streamlines, isotherms, local and mean Nusselt number. It can be seen that there was a real limitation to the existence of the inner body in trapezoidal enclosures. There is also a limitation of the action of the wavy form as an inner body.