Learning Forum

[Rajas]

Dear all,

I have been trying to mesh a complex CAD geometry in ANSYS Workbench Fluent, but could not succeed due to some errors. I used an additive manufacturing software (uses Open Cascade kernel) to generate the geometry, imported in .STEP format and performed all the repair functions in SpaceClaim before using ANSYS Meshing. I also have access to Autodesk Inventor, but I am not sure if I can perform any repairs therein.

I have attached images of the error and my geometry below. I heartily appreciate anyone's help in performing the repairs or finding a way out.

Thank you in advance.

Error - "Overflow or underflow in the arithmetic operation"

[Karthik Remella]

Hello Are you able to load the geometry in SpaceClaim? If so, right-click on the part and perform the check geometry operation. What does it show?
Also, try resetting your Meshing instance and see if this clears out the message.
Karthik

[Rajas]

Hi Karthik Yes, I am using SpaceClaim to load and repair the geometry. I have made some modifications to my geometry (Fig.1). I have performed the Check Geometry operation and there were no problems shown. I have also checked for other repair options (Stitch, Gaps, Extra Edges, etc) but everything seems well and no faults were found. I think I'm missing some subtle details.
Could you please elaborate more on the meshing instance, do you mean changing the size of elements?
I appreciate your help in all regards. Thank you!
Rajas
Fig. 1:

[Rob]

How many volumes have you got? The tree suggests you have one but the display is colouring the helical tube suggesting there are more.

[Rajas]

Hi Rob I initially had multiple faces (I believe) which on stitching formed a single volume. Yet the coloring is different. Apologies, I am using SpaceClaim for the first time and I am unaware of the significance of coloring.
However, I tried building a simpler geometry (Fig.1) and importing it with different import options (Fig.2) in Design Modeler. Default meshing is now possible (Fig.3). I'm not sure if this was the only cause for the meshing issue.
Nevertheless, the next big hurdle is to eliminate the extra edges causing the faces to separate. I assume this could cause problems with meshing and CFD analysis later.
I will be grateful to receive any guidance on the same, perhaps signposting to a similar thread? Thanks in advance.

Fig. 1: Single flow path geometry
Figure 2: Import options for Design Modeler
Fig. 3: Meshed geometry

[Rob]

I wouldn't worry about the extra edges, they shouldn't cause any problems for the tet mesher. I would be looking at curvature size functions and the growth rates plus inflation on the tube: the mesh above isn't good.