I am trying to run a cfd simulation for a water jet thruster i designed. I have imported the step file and created an external flow volume excluding the rotating region. I have then deleted the solid parts of the impeller and set up an MRF rotating region. I am trying to generate a mesh for this but it keeps failing without even starting, and the log is empty. Model has around 200 faces. I left the default settings on with fineness on 5. Estimated 1…3-2M cells. All default with standard algorithm and Physics-Based meshing
Hi @jtheocharides, thanks for posting on the forum and welcome to the SimScale Community 
I see you were able to generate the mesh for your model - could you share how you solved your problem?
If you’re still running into some issues, however, maybe a good option might be to increase the radius of this cylinder encapsulating the blades:
One initial attempt might be to set the radius 1.1 times larger than the ones from the blades!
Does that help?
Best,
Igor
An important part of the performance of the pump is the clearance between the wall around the blades and the blades themselves. If i make the radius of the cylinder any larger the walls will also be included in the rotating region which will give inaccurate results as the fluids friction with the wall will be different as the wall will also be rotating. The way i got the mesh to generate was by disabling physics based meshing, but the simulation wouldn’t run, probably because i did not set the rotating region as a cell zone. Now that i did, i get the same error even with physics based meshing off.
Hi @jtheocharides,
If you manually select the walls interferring with the rotating zone and set to them the Rotating wall boundary condition with a 0 rotational velocity:
It won’t be a part of the rotating region.
Best,
Igor
Mesh still fails to generate even with a rotating region that encapsulates the entire blades clearly, and overlaps with the walls as well.
I have tried something, cutting the shaft short so no part of the impeller sticks outside the rotating region. This time the mesh worked fine and i could run the simulation however it stopped at 12% saying that running conditions became unstable and the session was restarted.