Thank you for your suggestion regarding dividing my simulation. I will try to achieve my aim with this method.
Why ICFD?: I am designing cooling channels for a tool in hot forging process so I need a thermo mechanical simulation. I tried to simulate the mechanical bulk forming in 3D in LS-Dyna but I have been having issues with contact, remeshing etc. I found it easier to simulate (mechanical part) in another software but that software does not have CFD capabilities (thermal part). Hence I am implementing ICFD in LS-Dyna.
Why UNV?: My workpiece is initially in contact with several tools in the simulation and thus has a varied temperature profile. I am assuming it would be faster to take UNV temperature data instead of conducting a thermal simulation of the entire machine. Please feel free to correct me if my approach is not feasible.
There are not many examples of bulk metal forming for LS-Dyna. Regarding cooling, there is an example for tool cooling that I have derived from. I am sorry that I cannot provide you a proper reference.