Sensitivity study on three different SN order schemes of the discrete ordinates method for two-compartment enclosure fire

This paper presents a numerical study on the applicability of discrete ordinates method (DOM) for accounting the global radiative heat transfer of an enclosure fire in a twocompartment structure. The DOM employs Gaussian quadrature technique to approximate the radiative transfer equation (RTE). It is anticipated that by increasing the division of the solid angle and thereafter having more discrete radiation intensities, more accurate predictions could be attained. However, employing the higher approximation order (i.e. S8 scheme) requires 3.33 times the computational storage compared with the S4 approximation. Owing to the possible constraints of the computational storage capacity in personal computers, the approximation order should be chosen carefully a priori. The optimum choice of approximation order is investigated through sensitivity numerical studies of the S4, S6 and S8 approximations, which approximations correspond to 24, 48 and 80 fluxes, respectively.