minimal laakkonen case

[malihass]

Adding the 12 holes lakkonen case
@mjrahimi :

1. the first timestep does not run, probably because we need to slowly ramp up the impeller rotation, or because we need to start from the initial condition at 2s. Should we upload the initial condition at 2s, or should we leave it as is?
2. It would be better if we use the stir tank meshing module of bird instead of write_bmesh_file.py that way we don't have a lot of similar meshing scripts floating around.
   Thanks!

Co-authored by: mjrahimi

[mjrahimi]

I was able to run the case initially with omega=35 rad/s. Then after 2s flow time, I changed the rotation speed to 70 rad/s.

[mjrahimi]

So maybe change the MRFProperties to start with 35 rad/s so it does not crash when starting the simulation.