[aero_head]

Hello Everyone,

I was just wondering if anyone has seen this before/knows what would cause this. I have tried Googling this issue, but cannot find anything relevant.

When I am studying my .trn files in CFX-Post, there are strange discontinuities on two of my walls when I insert a plane directly onto them, appearing as though there are parts missing from it. The image attached depicts what I am seeing.

Other planes, even a small distance away, do not have this. Two of the walls on my domain display the plane as normal, and two walls do not even show a plane placed on them at all. When I make the domains visible in Post, they are solid and do not have this issue.

I meshed my geometry in ICEM with specified growth rates on the walls.

What could be the cause of this? I think it is affecting my simulation (i.e. not just a visual glitch), as the flow is behaving strangely around these areas.

[Gert-Jan]

Your picture is too small. Please increase size for better understanding.

[ghorrocks]

Based on your text, this problem should be visible on the mesh in ICEM. So go back to ICEM and review the mesh carefully in those areas.

[Gert-Jan]

I can't see what your problem is. I suspect it has to do with the surface normals of all elements. In ICEM, make sure the normals of all elements are consistent.


You can do this in Edit Mesh -> Re-Oreint Mesh -> Orient Consistently

[aero_head]

Hello Gert-Jan,

Sorry about that, I've zoomed in a bit and have made it so that the surface is now coloured for easier viewability.

[aero_head]

Hello ghorrocks,

Thanks for the suggestion, I will check out my mesh. I used the mesh law geometric 1/ geometric 2. Is it possible that my spacing I chose with my growth rate I set could be causing this issue?

[Opaque]

I seem to recall ICEM having issues to create perfect planar surface meshes.

Check the normals in ICEM, or even in CFD-Post and check if they are all the same, it is a plane, right?

[aero_head]

Hello Opaque,

Thank you for your suggestion. I have just performed the orient consistently option that Gert-Jan had suggested, and I will export it/set all boundary conditions in CFX-Pre and run it to see what it looks like in Post.

Yes, this image was of a plane (insert -> location -> plane) I had placed on the inlet/other surfaces of my domain. It looks like this for the inlet and bottom wall, planes on the right wall and the top wall show up normally, and the other two walls do not show the plane at all.

I will check all of the normals now. You are saying they should all be the same? If they are not, how do I fix that?

[Opaque]

Originally Posted by aero_head

...
I will check all of the normals now. You are saying they should all be the same? If they are not, how do I fix that?

Unfortunately, I am not an expert ICEM user. Hopefully, someone in the forum can help.

[Gert-Jan]

my second post tells you how to make the normals consistently

[aero_head]

Hello Gert-Jan,

As yes, that's right, thank you for that.

Is there a way to check the normals after I have performed this operation to ensure they are all the same?

[ghorrocks]

ICEM has many mesh error checks and consistent normals is one of them.

ICEM can do just about anything you like with a mesh, it is very flexible. Far more flexible than any of the other ANSYS meshing packages. But it is a bit hard to learn, so a bit of time is required to get the hang of it.

[aero_head]

Thank you ghorrocks! I'll look into the error checks ICEM can do. I've only used ICEM/ANSYS for about a year now, so I'm still learning.

[aero_head]

Hello,

I did a re-orient of my mesh and performed a short simulation, but the same issue occurs so it was not an issue with the surface normals.

I want to see if it has to do with how fine my mesh is in those areas, so I am going to coarsen it there a bit, however I do not see anything visibly wrong with my mesh in these areas.

[Gert-Jan]

Then I think we need to get more info on your case, and a clear picture of your geometry, and what you exactly did to create this picture. It could be quite normal but I can't judge base on the info you shared. So, now we are just guessing.

[aero_head]

Instead of placing a contour on a plane located at the inlet by specifying the x distance where my domain starts, I had to specify the plane via the drop down box to appear at my inlet. Then the contour plot shows up fine

[Gert-Jan]

If I understand you correctly, you created a plane on exact the same location as a boundary, the inlet in this case? Then your experience is the same as mine: this leads to strange pictures.

[aero_head]

Originally Posted by Gert-Jan

If I understand you correctly, you created a plane on exact the same location as a boundary, the inlet in this case? Then your experience is the same as mine: this leads to strange pictures.

Hello Gert-Jan,

Exactly. I placed a plane at the X-coordinate of my inlet (0 in my case), then inserted a contour plot on the Plane itself, rather than inserting the contour plot on the Inlet boundary. This minor change made all the difference. It only shows up with the contour placed on the Inlet. Disabled the appearance of the plane afterwards to see the contour plot in full.