Mesh doesn't show up properly in Paraview

ParaView Support
1

Hello,

I made a structured mesh in Pointwise 18.3. As you can see in this screenshort, the mesh near the wall is orthogonal and straight:

image
image881Ă—469 8.07 KB

However when I export it to OpenFOAM format and open it in Paraview 5.6 and 5.7 (using the builtin reader), it look like this near the walls:

image
image1016Ă—498 9.59 KB

The hight of the first cell, is approximately 1.8e-7.

Why is that happening?

Using checkMesh everything is OK:

Checking geometry...
    Overall domain bounding box (-20.25 -15.5 0) (80.75 15.5 0.05)
    Mesh has 2 geometric (non-empty/wedge) directions (1 1 0)
    Mesh has 2 solution (non-empty) directions (1 1 0)
    All edges aligned with or perpendicular to non-empty directions.
    Boundary openness (2.277920031e-20 -1.87383777e-19 1.150632749e-16) OK.
    Max cell openness = 3.88755667e-13 OK.
    Max aspect ratio = 104.8966563 OK.
    Minimum face area = 3.197058684e-10. Maximum face area = 2.13787771.  Face area magnitudes OK.
    Min volume = 3.197058684e-12. Max volume = 0.0213787771.  Total volume = 49.87393779.  Cell volumes OK.
    Mesh non-orthogonality Max: 16.55199107 average: 3.159688271
    Non-orthogonality check OK.
    Face pyramids OK.
    Max skewness = 0.3359864834 OK.
    Coupled point location match (average 0) OK.

Is it a problem with Paraview?

1 Like
2

@martink I suspect the small coordinates here are running into floating-point representation constraints. Thoughts?

3

Well, I confirm that the issue is with Paraview since the mesh shows up properly in both gmsh and when I re-import it again in Pointwise as OpenFOAM grid.

4

First thought would be ASCII format file somewhere in the mix. But aside from that, if I understand it correctly the mesh is roughly 100 by 30 with cells as small as 1.8e-7. That is an e9 difference in scale while float only supports about e7 resolution. So yes it could be a float resolution issue.

5

I tried both the ASCII/binary formats, but still getting the same issue.

6

Would it be possible to share a dataset that exhibits this problem? You can send it privately if you don’t want to post it publicly.

7

A fix for this is in VTK, just has to be exposed as a property in ParaView once it moves to that VTK.

8

In ParaView 5.9, there are new options to control coordinate shifting and scaling. Under the Display section of the properties panel for meshes, there is a new option called Coordinate Shift Scale Method. It defaults to “Auto Shift Scale”, which transforms coordinates once based on the bounding box of the data. When zooming in on the boundary layer, you want to change this option to “Focal Point Shift Scale” or “Near Focal Plane Shift Scale”, and the edges should look correct.

1 Like
9

Thank you very much for the explanation.

10

Hi, i have a similar problem.
When i move the mesh, the particles into the truck’s hopper move, but the mesh seems like dont move.
Please help me with this

Captura de pantalla de 2021-03-14 15-37-16
Captura de pantalla de 2021-03-14 15-37-161920Ă—1080 334 KB

11

Likely unrelated, open your own topic.