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Drawing multiple reference frames (tutorial)

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Old   March 30, 2020, 10:51
Default Drawing multiple reference frames (tutorial)
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I got some problems with drawing the geometry like in the tutorial 'using multiple reference frames.'

Tutorial.jpg

Could anyone help me with some advice on which one could be correct to draw the geometry for MRF?
and what are the non-overlapping interfaces?

Drawing.jpg
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Old   March 30, 2020, 11:23
Default Overlapping Domain
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Overlapping domains are allowed only with overset meshes, otherwise, you cannot use overlapping domains. As far as interfaces are concerned, ideally they should have 100% overlap. This is usually not possible because mesh is discrete. Therefore, only the first drawing is correct. The problem with the last one is that you will end up with single cell zone; i.e., you can either set whole of it stationary or whole of it rotation, leading to Single Reference Frame.
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Old   March 30, 2020, 23:55
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Quote:
Originally Posted by vinerm View Post
Overlapping domains are allowed only with overset meshes, otherwise, you cannot use overlapping domains. As far as interfaces are concerned, ideally they should have 100% overlap. This is usually not possible because mesh is discrete. Therefore, only the first drawing is correct. The problem with the last one is that you will end up with single cell zone; i.e., you can either set whole of it stationary or whole of it rotation, leading to Single Reference Frame.

Thanks.

I followed your comment, but I can not define two interfaces (red line and blue line), error message saying overlapping named selections should be resolved.

'The mesh file exporter does not support overlapping geometry in named selections. Please resolve the issue and try again.'

Following messages classified the second interface (blue line) to another group in mesh, which caused the interface not to appear and mesh interface in fluent not to be set with red line.

Could you tell me what's wrong with this?

drawing 1.jpg
Drawing 1_2.jpg
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Old   March 31, 2020, 04:55
Default Model for MRF
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You have a single body in your CAD model. For using MRF, each body should be separate, as mentioned in my previous post.
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Old   March 31, 2020, 05:20
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Quote:
Originally Posted by vinerm View Post
You have a single body in your CAD model. For using MRF, each body should be separate, as mentioned in my previous post.
Isn't it right? As recommended, I drew the blower with separate units.separate.png
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Old   March 31, 2020, 05:22
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What is implied by Units? Do you mean physical units or geometric units?

What's important is that the meshing should see three different bodies but if you open Meshing you will see that there is only one body.
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Old   March 31, 2020, 05:31
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Quote:
Originally Posted by vinerm View Post
What is implied by Units? Do you mean physical units or geometric units?

What's important is that the meshing should see three different bodies but if you open Meshing you will see that there is only one body.
Well, just forget the word 'units.'

I drew the geometry as in my figure with separate ones, which you recommended.
drawing 1.jpg

But in Meshing, it still showed just one body.

What do I have to do resolve this issue?
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Old   March 31, 2020, 05:42
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I don't know where you generated the CAD but if it is in DM, then just use Named Selections for individual bodies. That will maintain those as separate bodies. Other option is to ensure that all bodies are part of same part, however, keeping those in same part is helpful in maintaining good quality mesh and you won't have to use any interfaces.
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