Parts Based Meshing
 

Hey,

I have a pump which I want to mesh. The pump consists of some inner bodies and a Rotor inside the outer body. My idea was to work with parts-based meshing.

I got that STEP-file as one part. So firstly I used surface repair to remove free edges from the geometry. After that I generated via "split by patch" in the Regions tree several surfaces from my geometry and exported that surfaces as one part to the Geometry<Parts node.
Afterwards I created from that surfaces new parts in the Geometry>Parts Node.

The problem that I face now are new gaps (free edges) exacatly between my new defined parts.

Do you know why they appear and how I can fix them? Surface repair doesnt lead to a solution.

Thank you.

The picture shows the result after generating a Surface Mesh. Problem zone : Gap between Stator and main body.

Btw I'm new in Starccm + and not really sure about the procedure in working with parts-bashed meshing. I think that my procedure is wrong or one ore more steps are missing.

Lets say I have 3 different parts which represent one geometry and I want to generate at each part a different mesh. So how would the general workflow be?

To my knowledge this are the steps for generating different meshes on parts:

1. combine the parts to a Composite
2. create weak in-place contact between parts for achieving a conformal mesh between parts.
3. generate surface Mesh : Geometry<Operations<Automated Mesh select Surface Remesher and just select one specific part to generate mesh . In that fact generate another Automated Mesh node to create another mesh for a specific part.
4.Assign parts to one region.
5. Generate Surface Mesh.

Please tell me if I'm wrong.

Thank you.

No, I don't think you're using PBM correctly.

To STAR-CCM+, a "part" should represent either a solid or fluid volume. It looks to me that you've taken different surfaces and are using them as parts. Combine your separate surfaces into one part.

Now you say there's a stator, so I'm assuming something is rotating. If that's the case, you need to create a rotating part, and a non-rotating part. Use some of the general parts available in the parts tree to create a cylinder and subtract that from your original part to get a rotating domain.

Thank you for your reply. You a right there is an Impeller which is rotating.
I want to point out the my Geometry was imported as a STEP-File.

However my current state is that the surfaces (Impeller,Stator,Main body, Inlet,Outlet) are combined in one part now. Also free edges disappeared.

Do I really need a subtract of a Cylinder and my Part? That case is used to create an exterior domain right?
I think I should set up a rotating domain with subtracting a cylinder and impeller. which will fit in the main body of the pump.

Correct, you need to subtract the cylinder from your part to create a rotating domain.

Hey thank you. I face a lot of problems in setting up rotation. Do you know any Tutorial which could help me to understand how to set up rotation (rotation domains etc.) ?

There's an entire set of tutorials on motion available in the user guide.

Thanks., Have already worked with them.

The part which I m not really sure about is how to set up my rotating domain. Should it be for example a cylinder where exactly the volume of the Impeller (rotating part) is subtracted. It seems like that in the tutorial it is just a cylindrical concave boundary around the rotating part.


Here some examples of rotating domains which seem to be defined with just a cylindrical concave boundary around the rotating part.

You can do it either way. Which one you choose depends on how you want to treat the shroud, if any.

What is part based meshing? How should it be applied to the model?

Region-based meshing has been deprecated in newer versions of Star. It is retained only for reverse compatibility. Basically, only parts-based meshing is now relevant.


In the Star-CCM tree, there are parts which are mapped to regions. It used to be that you could generate a computational grid on the parts or the regions. On parts, it was parts-based meshing. On regions, it was region-based meshing. For the most part, they were identical. There were a few low-level meshing features that were allowed for the region-based mesher and not the parts-based mesher. These features are deprecated with the move towards parts-based meshing.