How to start simulation from 3d solid design from autoCAD

Hello Igor

Thank you for your reply for my question. I’ve read the recommendation you give to me. It help me a lot for my next simulation. But I want to ask you again. The recommendation you give to me was for simulation on outside of body if I understand it correctly.
My current project that I want to simulated is like a water treatment plant, but in simple design. And the simulation that I want to try is just like water flow inside the pipes and the plant. Do you have another suggestion for the problem? I wanna show you the image of my wtp design, but I the reply chat not allowing me to send media

Regards
Satar