Export of 2D Mesh to CGNS-file

Altair Forum User

Hello Guys,

 

I have the following questions:

 

- I just made a 2d Mesh and would like to export the mesh data for an external solver. This solver accepts CGNS-Mesh files. Is it possible to create a CGNS-file via Hypermesh Export?

 

- Is it possible to create a structured 2D Mesh in HyperMesh with quads in which the quads take their orientation from geometry (e.g. lines or curves) so that the Mesh is really clean and structured?

 

Thank you very much in advance!

 

Regards

tinh

Hi

Invoke pulldown menu File>Export>Solver Deck

select 'File type:' as CFD and select 'Solver type:' as CGNS

Altair Forum User

Thank you for your answer!

 

When selecting CFD I am only able to select AcuSolve/ Nastran (Acusolve). Perhaps the reason for this is that I am using the Student version?

 

 

Altair Forum User

I just found the options. Indeed, the student version is very limited when it comes to Export options: E.g. no CGNS export available...

Q.Nguyen-Dai

I confirm. Here's screenshot from our 'non-student' version:

 

Altair Forum User

After I tried to export my 2D CFD Mesh as CGNS (Unstructured) in HM, I am asking myself if HyperMesh is NOT able to export 2D CGNS-Mesh. Therefore I would really like to know if there is a solution for my problem:

 

My 2D mesh is for example looking like this:

Before exporting this Mesh, I wanted to set up Boundary Conditions (inlet, wall, outlet for example) and did it with:

• Selecting Quad elements at the border and organize them to each according component (inlet -->inlet, ...)
• ==>problems occured: 'Problem found in closedness of external boundary' and after that HM created an ^edges component with line elements on Border. When reading the CGNS file after export, the external solver says 'no internal elements found' but 'e.g. 4700 boundary elements found'. These 4700 elements, however, are the elements inside the defined boundary

 

• Therefore I tried another method: I organized the line elements of the created ^edges component to my different boundary components (inlet, outlet, ...) and defined the quad elements in the inside as normal FLUID
• ==>after trying to export this mesh (all elements visible) via CGNS, it says:

• ==>The 246 elements that are not allowed are the line elements at border from the ^edges component:

 

Now I am asking myself If HyperMesh can deal with a 2D Mesh export to CGNS with Boundary Information for the 2D Mesh... I am assuming that HyperMesh only wants to export 3D CGNS mesh (because there are always information windows like: 'no volume elements found' etc.)

 

Do you have any Idea?

 

 

Thank you so much in advance!

Regards

tinh

Why must you ask your self? just apply BCs to 2D mesh and try exporting it.

Altair Forum User

Yes, I really tried to give BCs to the 2D Mesh like that:

<?xml version="1.0" encoding="UTF-8"?>

 

However, during export (as described in my post before) it says 'free edges found' and when I continue the export and let the CGNS-Mesh be read by my external solver, the solver describes my inner 2D elements (here: green) as a boundary, but I defined the green elements as Fluid...

 

Therefore I think, that HM can only handle CGNS-Export of Mesh with 2D AND 3D Elements

 

I also tried it with 1D elements for the cylinder surface and the farfield (boundary outside of the 2D mesh --> see my last post): However, HM says that only 2D elements and 3D elements are allowed during CGNS-Export...

ssimo19

Hi, I have got the same problem and looking around on forums or manuals I still can't find the solution. Firstly, can I ask how you define/organize your boundaries and fluid components? do you simply create an additional collector and name it fluid* or boundaries? or do you  have to assign properties? 

 

Thanks.