Application of the modified discrete ordinates method with the concept of blocked-off region to irregular geometries

The standard discrete ordinates method (SDOM) produces anomalies caused by ray effects if the temperature of the walls has discontinuities or abrupt changes. Ray effects may be mitigated using the modified discrete ordinates method (MDOM), which is based on superposition of the solutions obtained by considering separately radiation from the walls and radiation from the medium. The MDOM has been used to calculate radiative heat transfer in irregular geometries using body-fitted coordinates. Here, the blocked-off region concept is used along with the MDOM to solve radiative transfer problems in irregular geometries. Two-dimensional irregular enclosures with curved boundaries, obstacles or radiation shields and containing a participating medium are considered. The accuracy of the results calculated using the SDOM and the MDOM is assessed by comparing the predictions with those obtained by other researchers. The results confirm the capability of the MDOM to minimize the anomalies due to ray effects in various situations. It is concluded that the blocked-off region concept can be recommended as a good option to solve radiative transport problems in irregular geometries.