Learning Forum

[yu272]

Hi all,

I am using Static Structural to simulate stretching of a tube to deform the inlet. After simulation, I tried to use the deformed geometry for FSI with Fluent. However, after I exported the deformed geometry into Design Modeler. I cannot add name selection to define inlet and outlet to create a fluid domain and Design Modeler gives an error.

This is how I exported the deformed geometry.

I set up a second Static Structure module and link the solution from the first Static Structure to the model of the new module, then in the Model, I clicked Geometry and choose to exported a pmdb file. Then, I feed pmdb file into a new Geometry module to modify it. 

Therefore, how can I modify based on a deformed geometry? I appreciate it if anyone can give me some suggestions!

Thank you!

Eric

[Sampat Kumar]

Hi Eric ,
It's possible that you need to fix your deformed exported geometry. It would be best if you could fix this exported geometry in Spaceclaim or Discovery. These two CAD applications automatically fix the geometry and are far more feature-rich and reliable. Additionally, name selection can be added in the SC and Discovery. However, if your strategy truly requires going through the DM, import the CAD file from SC or Discovery to the DM after reapir.

I think it's a geometry-specific issue, not a general issue.
Please try to follow the above approaches and let me know.
Regards,
Sampat

[yu272]

Hi Sampat,

Could you be more specifc on how the "fix" works? I imported the pmdb file into SpaceClaim and the deformed geometry now shows as a solid with mesh. Also, I lost the previously defined name selection, faces and edges on the geometry. Does that imply that I need to redo the sketching in SpaceClaim based on the geometry I imported?

Thank you!

Eric

[Sampat Kumar]

Hi Erick,
SC or Discovery tries to automatically repair parts and errors in the geometry while importing. You can repair the error manually in the SC or Discovery.
If you import the deformed geometry and open it into the SC, then all the previous name selections will be lost, so you have to recreate the sketching in the SC, but before that, you have to convert the faceted geometry into a solid model in the SC. 

Regards,
Sampat

[yu272]

Hi Sampat,

Thank you for suggestion! As a follow-up question. When I converted the faceted geometry into a solid, it keeps all triangular elements as faces. I found that I can merge the faces. Does that imply after I merge all elemental faces and keep the main faces I want, such as below:

Then I can directly used the solid to do FSI? However, sometimes I found that after manually merging elements (on the curved surfaces, as the auto merge tool does not work that well), the new curved face may show some curvature that was not appeared in the original structure.

For example, the stretched cylinder below show extra curvature on the right side, while the stretch itself is symmetric and the imported stl file geometry also symmetric. But after I merge the faces on the right side, it shows extra curvature.

How can I fix or avoid it?

Thank you!

Eric

 

[Rahul Mule]

Hi Eric,

Exporting the deformed pmdb file is better option here. Then opening it in SC you can prepare your geometry for FSI (create fluid geometry from deformed solid).

Convert to solid is not recommended for geometries having curved faces. For curved faces, you should create geometry by using different tools from scratch. 

You can refer to the following SpaceClaim Reverse Engineering Tutorials to know about building solid body from STL.

How apply a prestressed geometry in FSI? - Ansys Knowledge