Lower mantle dynamics is influenced a great deal by the pressure-dependence of material properties, such as viscosity, thermal expansivity , thermal conductivity and other pressure induced effects, like phase transitions. Today we will discuss the combined role of all of these components in an exploratory 2-D study with a finite-volume 2-D code cast in OPEN-MP and using a direct-solver Paradiso. A semi-Lagrangian method has been used to solve the temperature equation. Our goal is to find the proper mineral physical ingredients to stabilize mantle upwellings in the lower mantle in view of the strongly exothermic character of the post-perovskite phase transition discovered by Titech 6 years ago.