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-   -   Problem with extrude rotate tool (http://www.cfd-online.com/Forums/pointwise/116792-problem-extrude-rotate-tool.html)

Kio April 25, 2013 07:12

Problem with extrude rotate tool
 
2 Attachment(s)
Hi everyone,
I am new to pointwise so excuse me if the question is trivial.

I am trying to create a block of a hemispherical volume with a duct after using the extrude rotate tool to generate the hemisphere. Everything is ok except for the pole of the axis of rotation that causes a non-closed volume. I tried with the merge tool but it doesn't seem a problem with tolerance and I could not merge the two connectors.
Someone can help me?

Images attached, thanks

rmatus April 25, 2013 12:44

Might need to set appropriate CAE BC
 
Hi Kio:

I am not quite sure what you mean when you say the rotational extrusion creates a non-closed volume. Is this showing up when you import the grid into your CFD solver? If so, it might be because of the CAE boundary condition you have set along the singularity. Some solvers require a special boundary condition to be set for singularities. (Just guessing here, because I am not sure of the exact problem you are having.)

Looking at the pictures you attached, it looks like Pointwise created a true singularity (a pole domain - the blue line with dots inside circles at each end). If that is not what you want, let me know and perhaps I can help you get the grid you want.

Also, if you can provide more details about the nature of the non-closed volume you are seeing, e.g. what is the error message and what software is producing it, I will try to help more with that.

Thanks,
Rick

Kio April 26, 2013 04:45

Quote:

Originally Posted by rmatus (Post 423163)
Hi Kio:

Looking at the pictures you attached, it looks like Pointwise created a true singularity (a pole domain - the blue line with dots inside circles at each end). If that is not what you want, let me know and perhaps I can help you get the grid you want.

This is exactly the problem, how can I remove the singularity?
I use OpenFoam, but I guess the problem is the grid itself.

rmatus April 26, 2013 10:57

Change to a tetrahedral block
 
Zio:

I am not sure what other grid topology you are trying to attach the hemisphere block to, so it might be easier just to make it a tetrahedral block. To do that, delete the existing rotationally extruded block but keep its faces. Assemble all those faces, except the singularity, into a tetrahedral block and initialize it. That will give you a block with the same shape, but filled with tetrahedral cells.

Rick

Kio April 29, 2013 04:42

Quote:

Originally Posted by rmatus (Post 423355)
Zio:

I am not sure what other grid topology you are trying to attach the hemisphere block to, so it might be easier just to make it a tetrahedral block. To do that, delete the existing rotationally extruded block but keep its faces. Assemble all those faces, except the singularity, into a tetrahedral block and initialize it. That will give you a block with the same shape, but filled with tetrahedral cells.

Rick

This is just the problem, I want to make one tetrahedral block but there is the singularity that does not allow me to do that. I cannot delete the rotationally extruded block because it does not exist yet, so I cannot keep the faces. Is there another tool to create a rotationally extruded block that does not create a singularity?

rmatus April 29, 2013 11:59

Use existing domains to make a new block
 
Kio:

From your original pictures, it looks like you already have all the domains you need to make the tetrahedral block. Just pick all of them except the pole (singularity) and you should be able to assemble them into an unstructured block.

If that does not work, let me know.

Rick

Kio May 1, 2013 04:57

No it does not work, but I solve the problem. I create the hemisphere in database (rather of extrusion of connectors) and then project domains over that. In this manner there is no singularity and I can create one tetrahedral block.
Thank you anyway


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