Left: overshooting layer in simulation Hi1 represented by the shaded area between the radii of r_o,top and r_o,bot. The heavy vertical line shows the position of the boundary between the radiative and convection zones, indicated by the entropy profile produced by the one-dimensional stellar evolution calculation. The full line shows the enthalpy flux, scaled by the magnitude of the large negative peak. The dashed line shows the Schwarzschild discriminant S(r), scaled to appear on this graph. Right: Schwarzschild discriminant in simulations Hi4 and Hi5, compared with the value obtained from the one-dimensional model of the young sun.