Regarding the importance of radiation in contemporary technology of the world, this paper presents a finite difference solution for geometric optimization of a radiative enclosure. In this regard, produced foams during glass melting process are one of the important factors for optimization of melting process and final product quality. On one hand, these foam causes prevention of some part of radiation energy from combustion to glass melt and also leads to increase in fuel and decrease in furnace output. On the other hand, they put high damages to final glass products. For designing a radiant enclosure, the radiative two-flux equation is coupled with the transient energy equation and radiation transfer equation (RTE).