So, first we have to calculate the heat flux at the wall and that is a boundary condition for our model, which we have shown in the theoretical part. And the heat flux of the wall is given by the sum of convective heat transfer radiative heat transfer, mutual radiation and smoke radiation.
Here the expressions are given and what we need are the exchange coefficient which we have between fire an wall and also between smoke and wall and between wall and wall, because we have a mutual radiation.