Summary of the interior structure of the convective core of a 5 M_⊙ main-sequence model, calculated with the 3-equation model. The dashed black line indicates the Schwarzschild boundary. The different panels show: (a) the TKE, (b) the convective flux variable, (c) the super-adiabatic temperature gradient, and (d) the diffusion coefficient according to Eq. (5). The selected stellar model has a central hydrogen abundance of X_c = 0.6. The inset in panel b shows the region of negative convective flux just beyond the Schwarzschild boundary.