Flow acceleration by imposing flow channelization structures like chimneys and/or solid barriers to improve natural convection cooling in pure fluids, is a well-known technique and a thoroughly investigated topic in thermal engineering. However, accelerating flow through porous media, by using such a passive technique, is challenging due to restriction imposed by the solid matrix to the erection of such structures. This study is a unique investigation into a passive method to accelerate flow in natural convection cooling through a bottom-enclosed porous medium with a vertical heated structure at the center, a configuration that is commonly encountered in industry. The porous domain is divided into distinct zones varying in porosity while retaining the average porosity of the original system, to ensure enough structural stability to the vertical heating element. Employing computational fluid dynamics (CFD) analyses, the study shows that the method has the potential to significantly improve natural convection cooling by accelerating flow in tall porous structures while at the same time improves mechanical stability of such structures.