Time-averaged radial profile, produced from a volume-weighted average in the angular direction, of specific entropy in simulations Hi4 and Hi5. A heavy vertical black line marks the boundary between the radiative and convection zones, determined from the radial profile of entropy and the Schwarzschild criterion produced by the one-dimensional stellar model. A gray vertical line marks the inner radial boundary of the spherical shell at 0.21 of the stellar radius.