I want to simulate a closed box in SimScale where no air enters or leaves the domain. Inside the box, there are four fans, and the goal is to have them circulate the air internally.
My confusion is:
Since the system is closed, I do not want to define any inlet or outlet boundaries.
How should I set up the boundary conditions in this case?
For the fans, should I use a fan boundary condition, momentum source, or rotating region?
What is the correct way to represent multiple fans in an enclosed volume so that the solver does not complain about continuity errors?
Any guidance or example workflows would be very helpful.
Let me try and answer your questions as best as I can.
→ Since the system is closed, there is no need to define any boundary condition to spcify an opening, you can leave them undefined
→ Since you said there aren’t openings and the air is just recirculating within the domain, you shouldn’t use the fan boundary condition. If you were to use it, you’d be inserting mass into the system which wouldn’t be able to leave it
→ You could use either a momentum source or a rotating zone. The difference is that a momentum source will accelerate the fluid but won’t model the actual fan behavior (fluid-blades interaction) whereas the rotating zone will. If you’re not concerned with that, just go with the momentum source approach for simplicity
→ As momentum sources or rotating zones. Continuity errors will appear if mass is not conserved (e.g. you have an inlet but no outlets)