Hey @all,
I have a simple question. For CFD Simulation, do I always need a solid body? Or is it also possible to simulate with a hollow body? I have a hollow body, but then don’t know where to set the boundaries.
Would be happy about any recommendations.
this is the project : TEST3 by NickNol | SimScale
Thank u in advance !
Nick
Hi @NickNol, thanks for posting at our forum 
You can run a simulation with your geometry but for that you’ll need to create an Internal Flow Volume. The fluid will be simulated on the negative of your model, so that you’d need another model to express that.
That operation is also done in this tutorial.
However, you’re trying to run an Incompressible analysis. In your case, then, you’d have to delete all of the bodies which are not the flow region, since that kind of analysis does not consider any kind of interaction between fluid and solid parts.
Does that help?
Best,
Igor
Hey Igor,
that already helped a lot and thanks for linking the Tutorials. Got a better understanding now.
I tried to do what you mentioned with the bodies, but came over this : “A setup with at least 2 regions is being used in a single-region analysis type. Please delete CAD regions that are irrelevant for the simulation. If all CAD regions are relevant, ensure that only one region is assigned to the material and that all other bodies are assigned to advanced concepts.”
What is meant with the advanced concepts?
Thx very much in advance.
Nick
Hi @NickNol,
When running an Incompressible Analysis, we can’t leave solid bodies on the simulation other than the flow region, since you’d only be interested in the flow behavior in that sort of analysis.
As to your question
Advanced concepts are cell zones in which the flow will behave differently (such as the application of a rotation), more on that here. That would solve the multiple CAD issue because the solver “discards” the solid chosen as an advanced concept and only considers the region it encloses for the application of the different cell behavior.
Best,
Igor
