Thank you so much for your reply, Robert.

I have been reading Dr. Amine's and your comments on different topics in the forum in the past few years. I am so excited that you are helping with my problem now!

Unfortunately, I couldn't upload the photos with the description. I even tried uploading them on google drive and sharing the link (even though I know you prefer not to click on the links) but that didn't work either. Do you have any idea on how I can share the photos? It'll help a lot with the illustration of the problem.

I have cylindrical walls (representing screen wires) that are subtracted from the bulk air duct. The wire diameter is 100 microns and the screen opening is 200 microns. My domain is purely made of air with the walls subtracted. The walls are solid and not porous and a "trap" DPM boundary condition is applied to them. Therefore, neither the flow nor the particles pass through them. Yes, I am trying to count the number of the particles that will hit the walls and then will be eliminated from the domain and will be counted as captured in the report.