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zeophlite July 9, 2013 05:37

Inflation created stairstep mesh at some locations.
3 Attachment(s)
I have a reservoir with a pipe coming out of it. I'm using Automatic Inflation and Advanced Size Function. The walls of the reservoir and the pipe are set for inflation. The inflation layer along the wall and the pipe are correct, but they do not join correctly at the connection.

This is causing stairsteps, as well as a high skewness.

I've taken a screenshot of the options I have for meshing. What do I need to set for the boundary layers to connect around the bend?

mjgraf July 9, 2013 21:18

in ICEM I would control that with
Min prism quality
Max prism angle
Max height over base

you may want to try setting "Maximum Angle" to 180.

zeophlite July 9, 2013 21:26

Hi mjgraf,

Thank you for your quick reply. Is there a similar option in Ansys Meshing?

mjgraf July 9, 2013 21:37

that's why I suggest
"you may want to try setting "Maximum Angle" to 180."

zeophlite July 9, 2013 22:14

1 Attachment(s)
Hi mjgraf,

Cheers, I didn't realize you were talking about Ansys Meshing in your second paragraph - I'm quite new to this product, and most of those settings are just their defaults. I set Maximum Angle set to 180, and in a different area of the geometry that was also stairstep'd, the new mesh now has a correct boundary layer.

However, now the entire reservoir does not have its boundary layer (beforehand it did, just was stairstep'd at the outlet). The pipe and the reservoir are separate bodies in the same part. In the previously shown area, I get the attached mesh and the below errors:
  • Inflation created stairstep mesh at some locations.
  • Pre-inflation failed possibly because inflation thickness is larger than adjacent face height.

When I right click on the "Pre-inflation..." warning and select "Show Problematic Geometry", it selects just the right hand wall displayed in the attached image.

mjgraf July 9, 2013 22:56

Didn't realize those were two bodies, assuming Ansys Meshing is primarily ICEM in the background.... you can not have that surface interface at that location you created and have the prism inflate off those two walls and into the internal surface interface. I ran into this before in ICEM and needed to move my internal surface or create one continuous domain/body.

searched my email from support back then:

You are extruding prisms from the two walls and also capturing the mesh on internal surfaces. This causes a constraint for the prism mesher. (If you do not have the int-wall, at the corner, prism can wrap around by splitting the angle. Capturing a internal wall there does not allow splitting the angle in that location)
hence the stair stepping.
so merge your two bodies into one or move that interface to the right some to create a nub on the reservoir. Not sure how your model is setup or how Ansys Meshing works. In ICEM, if these were two imported parts, I would just delete the surfaces at the interface and create a single body part, done.

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