Hey @Malthe_Larsen ,
I can see you were able to run simulations with vortex generators on the roof already.
Some tips however:
The best way would be to design it as a separate part in whichever CAD tool you use and then importing the assembly into SimScale and then creating a flow region.
What you can also do is have all the VGs ( vortex generators) separately imported into SimScale to test only the flow around them in few runs, and use the best one then along with the entire car to save simulation effort. You can use the Add CAD feature to add any CAD (any of the VGs) in the project to another CAD (your car) in the project. You can also use Boolean operations within SimScale to union two solids, for example.
Let us know if you need more support with your project!
Best,
Satvik