CFD Simulation Mesh of propeller

[andi5785]

Hello,

I try to simulate the air flow in a closed chamber with a rotating propeller and some walls.

Project link: SimScale

Walls and propeller are deleted by boolean operation from the bounding area and I created a rotating cylinder. The problem is, that when meshing is finished, the walls of the propeller are omitted. Is there any suggestion about a solution? When meshing with a boundary box instead of the outer wall everything is fine.

Any suggestions?

Thanks

Andreas

[jousefm]

Hi Andreas!

I saw that in the latest mesh settings the walls and the MRF remain in the mesh, did you figure out the issue by yourself then or am I still missing something?

Best,

Jousef

[andi5785]

Hi jousefm,

I tried two more times:

1. I build the rotating cylinder around the other wall part. The result is the same, the inner walls will be omitted. Thus, I suppose, the cause for not-meshing is related to the rotating cylinder.
2. I tried to build the rotating cylinder by using geometry primitives, but this doesn’t work.
3. I tried to move the origin of the rotating cylinder to the outer wall of the fan surface. Still no meshing.

Regards

Andreas

Additional: I also tried to activate Multi Region Meshing. Then meshing is done properly, but simulation is not running

[Retsam]

@andi5785: please read description of similar project I did last year:

Internal CFD with MRF (2019)

Cheers,

Restam

[andi5785]

Hi Retsam,

thanks for your reply. I already knew your project and adapted most of that Thanks for that.
So the only difference is that I can not put the rotating cylinder to the external region. Maybe this it is? The rest seems to be very similar for me.

Anyway I now found out that its working when I define a surface refinement to the rotating cylinder with cell zone. It seems that the rotating cylinder is “shadowing” the rest otherwise.

Simulation is running now.

Regards,

Andreas

[Retsam]

@andi5785

I define a surface refinement to the rotating cylinder with cell zone

That is the correct way to define MRF zone. Great.

[andi5785]

Just want to add that useful link for MRF for other users:

Implementing the Moving Reference Frame (MRF) Approach

Introduction The Moving Reference Frame (MRF) approach is a steady-state method employed in industrial Computational Fluid Dynamics (CFD) to model problems with rotating parts. It is considered to be less computationally expensive and yet accurate enough for most industrial problems. The underlying physics behind this approach is simple, yet elegant. A thin volumetric region of mesh cells is created around the rotating body during the meshing phase. This region is known as the MRF zone. [imag…