[subham998]

I have been trying to implement the DO Radiation Model to simulate a radiation beam in Ansys Fluent since the past 1 month without much success. The computational domain consists of a cylinder of 10 cm radius and 1 m length and the front section of the cylinder is specified as irradiated wherein incident radiation enters the domain. Air and dust particles are present inside the cylinder.

I have set the absorptivity of air to zero in the simulation, and the theta and phi extent corresponding to the beam width is set to 1e-06. I have also set the theta and phi pixels and divisions equal to 15. I am expecting the incident radiation to be constant intensity over the entire domain, however, I what I am observing is that the intensity of incident radiation decreases with the axial length, and finally attains a constant value after a certain distance.

I would highly appreciate your support in solving the issue. Please let me know in case any additional information is required.

[sbaffini]

Any particular reason to not use the actual DO already present in Fluent?

[subham998]

I am actually using the DO radiation inbuilt in Ansys Fluent. Apologies if it was not clear in the question

[sbaffini]

It's just that "implementation" typically refers to the work of making available something that wasn't before the said work.

Can't give you much help on the rest. Surely, your question belongs more to the Fluent forum than here