Numerical Simulations of Double-Diffusive Convection with Astrophysical Applications

Full text: Double-diffusive convection plays an important role in mixing processes of astrophysical and geophysical flows. One example for it is semi-convection where a stable mean molecular weight gradient due to a variable helium abundance counteracts an unstable temperature gradient and thus modifies the transport of heat and helium concentration due to convection. This physical process occurs near the core region of massive stars and hence influences the chemical evolution of the progenitors of core-collapse supernovae. To investigate this physical process which has traditionally been described by highly parametrized, mixing length type models, we use the ANTARES code and perform hydrodynamical simulations of semi-convection in an astrophysically relevant parameter space. We describe the numerical techniques which have been investigated and implemented, as well as several types of simulations set up for parameter studies and for the investigation of the basic physical processes, and perform some comparisons with simple astrophysical models. (author)