  We present the first detailed three-dimensional hydrodynamic implicit large
eddy simulations of turbulent convection for carbon burning. The simulations
start with an initial radial profile mapped from a carbon burning shell within
a 15 solar mass stellar evolution model. We considered 4 resolutions from 128^3
to 1024^3 zones. These simulations confirm that convective boundary mixing
(CBM) occurs via turbulent entrainment as in the case of oxygen burning. The
expansion of the boundary into the surrounding stable region and the
entrainment rate are smaller at the bottom boundary because it is stiffer than
the upper boundary. The results of this and similar studies call for improved
CBM prescriptions in 1D stellar evolution models.
