Add radiation to tutorial ACU-T 6103 AcuSolve - EDEM Bidirectional Coupling

Hello,

I have tried the tutorial ACU-T 6103 AcuSolve - EDEM Bidirectional Coupling with Heat Transfer

https://2022.help.altair.com/2022.3/hwcfdsolvers/acusolve/topics/tutorials/acu/acu_6103_intro_cfd_r.htm

And I was able to use the bidirectional coupling for my system, where I have a horizontal cylinder filled with some ceramic particles in contact with the cylinder wall. My cylinder is at ~600K, so I want to consider the radiation effect to my particles. Please advice how to add radiation.

Then I looked into another tutorial with radiation ACU-T 3202

https://2022.help.altair.com/2022.3/hwcfdsolvers/acusolve/topics/tutorials/acu/acu_3202_intro_cfd_r.htm

and I have some questions:

1. What radiation model shall I use, Simple, or P-1, or Discrete Ordinate? Say my cylinder is steel
2. In the 6103 tutorial, the material is Air-Particle EDEM 2-way, the same for my system. Then if I want to add radiation, I would need set the material for my cylinder wall as steel. I cannot overlap the material. How can I do this?
3. Shall I make my cylinder wall with a thickness, similar to the outside sphere in Tutorial 3202?

Could you please give me some suggestions and detailed instructions?

Thank you!