ASSESSMENT OF THE P-1 APPROXIMATION IN COLD-WALLED ENCLOSURES WITH INTERNAL HEAT-GENERATION

The accuracy of the P-1 approximation in modeling the radiative temper ature distribution within an absorbing, emitting, and isotropically sc attering medium with internal heat generation is assessed Geometries e valuated include parallel flat plates, an infinite cylinder, and a tru ncated cone. P-1 results are compared with Monte Carlo solutions. The results presented give solid evidence that the P-1 method is a very go od approximation to the radiative temperature distribution within a pa rticipating medium with internal heat generation. The literature revie wed limits the use of the P-1 approximation to media that are opticall y thick. The results presented here show that the P-1 approximation ca n be used effectively for optical thicknesses in the range 0.1 less-th an-or-equal-to tau less-than-or-equal-to 2.0 for infinite parallel fla t plates, and 0.05 less-than-or-equal-to tau less-than-or-equal-to 5.0 for cylindrical and conical geometries.