Formation of layered structures in double-diffusive convection as applied to the geosciences

We have studied the different scenarios for layered structures to form or be destroyed in time-dependent, double-diffusive convection for an infinite Prandtl number fluid. We have concentrated on the subcritical diffusive and finger regimes and examined the thermal-chemical evolution as applied to magma chambers. Both cooling from the top and side boundary conditions have also been examined. Subcritical double-diffusive convection yields the most favorable conditions for layering. A sufficiently high chemical buoyancy ratio keeps the layering intact and yields a small Nusselt number. Double-diffusive convection in the subcritical regime can lead to layering from an initially unlayered state. There are no evidences for layering in the finger regime. Finally we present a new result dealing with the potentially important role played by viscous dissipation in double-diffusive convection, as found in the Earth’s outer core and crust.