Combined convection-radiation problems in gray absorbing/emitting/scattering media are investigated numerically. The discrete ordinates interpolation method (DOIM) is incorporated into commercial software (FLUENT) using userdefined functions (UDFs). As preliminary tests, combined conduction/natural convection-radiation problems in a rectangular geometry are solved to validate the accuracy. The original DOIM is modified to solve the radiative heat transfer in an irregular geometry with internal obstacles. Then the combined turbulent forced convection-radiation problem is solved, and the radiation effects are discussed through the profiles of velocity and temperature. Fine agreement with other reference solutions is found. The DOIM promises reliable accuracy and excellent versatility for incorporation into fluid flow codes. Further computational issues are also discussed.