We are doing underhood thermal management calculations using an in-house unstructured CFD code without on-board radiation modeling. We wish to couple the flow model to a surface-to-surface radiation analysis, but feel that the CFD resolution (5 million volume elements, over one million surface triangles) is too fine for a ray tracing based radiation analysis. So we need some sort of surface grid agglomeration in additino to the radiation software. Any recommendations?

Have you looked at Radthemrm? I think it may do what you are looking for (if i understood your question right).

Raza, what is 'Radthemrm'?

Radtherm is a commercially available radiation code. Unfortunately i do not know the company's name that makes this code. it is used in automotive industry. it does a good job with surface-to-surface radiation. There are several convenience features built into it.

Hi Rob,

I did such a coupling for a structured BFC grid in a commercial code (PHOENICS). It consists of first identifying the matching between the CFD cell faces with each radiation surface element. Then, during the calculation process, conservative interpolations should be used to pass the averaged temperature to the radiation calculation (emissive source), and pass the radiative flux back to the CFD solution as an energy source.

In principle, the same should be done for unstructured grid, but it should be more complicated to program. Also, if you wish to allow for other than one-to-many cell correspondence, greater care should be excercized in interpolation so as to preserve energy.