radiation

ritmat

hi, I have a model wich combine natural convection and radiation. It is enclosed volume ( actually one of the surface is an outlet for radiation but there are no real wall but because there are no flow of air inside the volume , i assume it being wall). So one face is at more than 1000 degC (from where is coming the radiation), and i want to see how this face is going to radiate the entire volume. But for my bondary conditions i assume the temperature of the others face: the side wall at 110 deg C (because of cooling) and the outlet wall (actually not real wall) at 300 degC (just a guess). I am using DO model, but i cant get convergence. I would like to have some advice from you to set up my model. I tried to follow the tutorial 5 of fluent, but first their gradient of temperature is less important and secondly i dont get why they adjust the value of g. Thanks for your help cos i am really screwed .