Learning Forum

[ecrod]

Hello All.

I've imported my mesh in *.bdf format into Fluent 19.2. However, it is showing  rendering issues.

I have no idea what it means. Could someone help me to figure out how to solve it ?

Thanks in advance.

[peteroznewman]

I expect this is just the way ANSYS tries to group element faces into "surfaces".

I expect if you just plot the elements, you get a sensible looking mesh.

If you put the .bdf file into a .zip file, you can upload it to your post.

[ecrod]

This a simple annular example of Nastran bulkdata file containing rendering issue. Indeed, I am interesting to figure out what is going on for this geometry as well.

File attached both simple annulus and my annular geometry (washout_v2.bdf)

[peteroznewman]

I opened each of these BDF files in Femap, which is very good at reading NASTRAN files. Attached are the error reports on those files. The element shapes are very poor.

I recommend you create some new geometry in either DesignModeler or SpaceClaim and mesh that in ANSYS.

[ecrod]

Can I code in DesignModeler or SpaceClaim ? Or is it only a Graphical User Interface ?

 

[peteroznewman]

I don't write code myself, but I know SpaceClaim has a script capability and an API.

 

   

[ecrod]

I realized, for instance in annulus example, that the mesh looks like fine and the issue is only visible for interfaces view (walls) ?

[peteroznewman]

The quality of the element shape is poor on some elements. For example, the element faces on the inside cylindrical face have a high level of skew. The entire mesh would be improved if it was Hex elements instead of Tet elements.

[ecrod]

Peter,

Why when I "Check Case" from Fluent Run Calculation tab, It does not show skewness message  issue as "Skewness exceeded 0.98 at "number" cells"  ?

I receive a message :  No recommendations to make at this time.

[peteroznewman]

Okay, it is not so bad that Fluent refuses to solve, but the entire mesh would be improved if it was Hex elements instead of Tet elements.

[ecrod]

Peter,

I realized that these artifacts are only visible if in Fluent Launcher I set "Parallel" in Processing Options. Otherwise, everything is fine.

[ecrod]

Hello Peter,

Do you have any idea why it is happening only in Parallel mode ? This is only a visualization issue or could have effect in computation as well ?

Thanks.

[peteroznewman]

I have no idea, but if I was going to make up a reason, I would say that those scraggly lines show how the computational domain was broken up for the multiple processors.