[Other] Importing GIS CAD file into ANSYS

bv169 · May 1, 2020, 09:48

Hello,

I am working to import the bottom topography from an area of the ocean into Fluent so that I can use it in a model. I have been able to manipulate data in arcGIS and export to STL files to import to SpaceClaim, but when I import the files they are flat faceted bodies, and do not have the proper elevation.

I am wondering if I should be using a certain coordinate system in GIS when exporting the files, or if there's some sort of changes I can make to adjust the facets after importing?

I'd appreciate any advice on how to complete this task, as I am pretty stuck.

Thanks,
Breanna

Gert-Jan · May 1, 2020, 10:39

You need to create a solid model in Spaceclaim. But that can quite a hassle.
I would never do that. I would import the STL in ICEM and try to mesh it there. This is quite an ancient program, but it works lovely, if you know how to use it............

bv169 · May 1, 2020, 10:47

Thank you for the suggestion! I'm not familiar with ICEM. I checked the ANSYS site and it says it is for meshing only, would I need to first still create a geometry, or should the STL files be able to be imported and meshed directly?

Gert-Jan · May 1, 2020, 11:15

The great advantage of ICEM is that it works with surfaces. So, you don't need a solid. In your case, you can get away with 6 surfaces: 1 top, 4 sides and a bottom (your STL).

You can create these in ICEM. That is not too difficult: create 4 points -> connect them to create 2 lines -> connect them to create 1 surface. Easy.
Alternatively create the surfaces in Spaceclaim, or similar.

In your case, you would have a hard time to create exact matching side surfaces, since the top surface is flat and the stl-bottom-profile is spiky. However, the funny part is that in ICEM the edges of the surfaces to not need to match exactly. Your side surfaces can be rectangulars that go beyond your stl-bottom profile. E.g., with your sealevel at 0m, your spiky bottom profile can be at -50m (on average), your sides surfaces can extend up to -60m. In other words: they do not have to have anything in common. They need to intersect. That's all. The only requirement is that the 6 surfaces enclose a volume. There may not be a gap.

Then in this enclosed volume, ICEM can create a mesh. Look at the tutorials how.

Gert-Jan · May 1, 2020, 11:30

Like in this figure with in blue the ocean surface and brown your STL bottom profile.

May 1, 2020, 09:48	Importing GIS CAD file into ANSYS	#1
bv169 New Member Breanna Join Date: Oct 2019 Posts: 4 Rep Power: 6	Hello, I am working to import the bottom topography from an area of the ocean into Fluent so that I can use it in a model. I have been able to manipulate data in arcGIS and export to STL files to import to SpaceClaim, but when I import the files they are flat faceted bodies, and do not have the proper elevation. I am wondering if I should be using a certain coordinate system in GIS when exporting the files, or if there's some sort of changes I can make to adjust the facets after importing? I'd appreciate any advice on how to complete this task, as I am pretty stuck. Thanks, Breanna

May 1, 2020, 10:39		#2
Gert-Jan Senior Member Gert-Jan Join Date: Oct 2012 Location: Europe Posts: 1,835 Rep Power: 27	You need to create a solid model in Spaceclaim. But that can quite a hassle. I would never do that. I would import the STL in ICEM and try to mesh it there. This is quite an ancient program, but it works lovely, if you know how to use it............ bv169 likes this.

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May 1, 2020, 10:47		#3
bv169 New Member Breanna Join Date: Oct 2019 Posts: 4 Rep Power: 6	Thank you for the suggestion! I'm not familiar with ICEM. I checked the ANSYS site and it says it is for meshing only, would I need to first still create a geometry, or should the STL files be able to be imported and meshed directly?

May 1, 2020, 11:15		#4
Gert-Jan Senior Member Gert-Jan Join Date: Oct 2012 Location: Europe Posts: 1,835 Rep Power: 27	The great advantage of ICEM is that it works with surfaces. So, you don't need a solid. In your case, you can get away with 6 surfaces: 1 top, 4 sides and a bottom (your STL). You can create these in ICEM. That is not too difficult: create 4 points -> connect them to create 2 lines -> connect them to create 1 surface. Easy. Alternatively create the surfaces in Spaceclaim, or similar. In your case, you would have a hard time to create exact matching side surfaces, since the top surface is flat and the stl-bottom-profile is spiky. However, the funny part is that in ICEM the edges of the surfaces to not need to match exactly. Your side surfaces can be rectangulars that go beyond your stl-bottom profile. E.g., with your sealevel at 0m, your spiky bottom profile can be at -50m (on average), your sides surfaces can extend up to -60m. In other words: they do not have to have anything in common. They need to intersect. That's all. The only requirement is that the 6 surfaces enclose a volume. There may not be a gap. Then in this enclosed volume, ICEM can create a mesh. Look at the tutorials how.