I have a model involved solid, fluid, radiation and heat conduction. I use CFX5 to solve it. But, I could not get good converged solution. RMS for most of the domains just stayed unchanged after several iterations and could not go lower than 1e-4, and the RMS for radiation even could not go lower than 1. I would highly appreciated it if someone could help me. I have been struggling at this problem for weeks. And, it seems that CFX support could not give me too much support at this problem. Thank you very much!

Dear Jay,

From your description is not very clear what you are doing, for example:

1 - What kind of flow you have: laminar or turbulent, natural convection or forced convection driven.

2 - Solids? How many? Are they of many different materials with a wide spectrum of thermal conducticvities?

3 - Radiation? Which model are you using? If MonteCarlo, is there radiation in the solids? What is you optical thickness range, thin or thick?

4 - An RMS of 1.E-4 is not perfect, but it is not bad either. Then, there might a subtle physics or numerics issue which is not easy to infer from your description.

I would organize your available data and contact CFX support again.

Good luck, Juan Carlos