Giant planet evolution: the effect of convection and mixing

We model the long-term evolution of giant planets
accounting for the change in the compositional
gradient with time. Core erosion is modeled by
convective-mixing using both the Ledoux and
Schwarzschild criteria for convection. We find that in
some cases compositional gradients prevent
convective mixing, and as a result, the assumption of
an adiabatic interior is no longer valid. In other cases,
mixing leads to layered-convection, which results in
a stair-like internal structure and a slower cooling [2].
In addition, the process of mixing (if it occurs)
enriches the gaseous envelope in heavy elements
from the core. These have a direct effect on the
planetary evolution, and therefore on the planetary
radius and luminosity. We suggest that the memory
of the primordial internal structure remains even after
billions of years.