Rafael’s research is focused on how composition gradients affect the mixing and transport properties of stellar fluids. One of the most important problems in astrophysical and geophysical fluid dynamics is the modelling of heat and composition transport in turbulent regions. In this context, thermal convection in a chemically homogeneous fluid has been studied extensively and corresponding transport properties are well understood. However, there are many unanswered questions about convection in the presence of additional physics such as rotation and composition gradients which are important for astrophysical and geophysical systems. The effects of composition gradients on convection have been proposed to explain some of the observed properties of giant planets, such as Jupiter and Saturn. For example, the inflated radii of hot Jupiters, the over-abundance of metals in the outer parts of Jupiter and Saturn, and the thermal luminosity of Saturn differ from theoretical predictions of fully convective giant planets. In this context, a composition gradient might develop from either their formation history or collisional events during their evolution. Rafael and professor Andrew Cumming are performing numerical experiments to reveal whether the gaseous envelope of giant planets can become fully mixed during their cooling evolution.