divergence of radiation flux
 

Hi, I have a question about radiation heat transfer in FLUENT.

I solved my CFD Problem with DO radiation model. (axis-symmetry)
The calculation was completed successfully.
I would like to plot the divergence of radiation flux along to r direction in fluid region.

How can I do?
I cannot find out the given menu by FLUENT about the divergence of radiation flux in fluid region.

and I don't know the macro names(Ib,G) for UDF.

The equation is as follows,

div F = k*(4*pi*Ib-G)

F : radiative flux
k : absorption coefficient
Ib : spectral black-body intensity
G : incident radiation