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Parts Based Meshing

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Old   May 15, 2014, 08:50
Default Parts Based Meshing
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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.

Last edited by skapetan; May 16, 2014 at 04:31.
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Old   May 15, 2014, 09:41
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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.
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Old   May 15, 2014, 21:58
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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.
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Old   May 16, 2014, 07:54
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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.
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Old   May 16, 2014, 12:40
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Correct, you need to subtract the cylinder from your part to create a rotating domain.
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Old   May 21, 2014, 09:59
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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.) ?
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Old   May 21, 2014, 10:41
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There's an entire set of tutorials on motion available in the user guide.
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Old   May 26, 2014, 03:44
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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.
Attached Images
File Type: jpg example 1.jpg (20.9 KB, 71 views)
File Type: jpg example 2.jpg (15.2 KB, 76 views)
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Old   May 26, 2014, 23:27
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You can do it either way. Which one you choose depends on how you want to treat the shroud, if any.
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Old   January 12, 2022, 14:04
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What is part based meshing? How should it be applied to the model?
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Old   January 12, 2022, 15:55
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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.
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