U-V Curves Issues

Categories // Simulation, Tips & Tricks

Mess with Meshes Trouble Shooting

Written by:  Shaun Bentley, Application Engineer

Sometimes when you mesh your model (particularly imported geometry) the mesh can look pretty strange or might even fail. Sometimes these problems can stem from the natural u-v curves of complex surfaces. To demonstrate this idea, can you tell the difference between the two bodies shown below?

Figure 1 - Topologically Equivalent Bodies
Figure 1 - Topologically Equivalent Bodies

To reveal the difference, compare the mesh quality of the Standard (figure 1), Curvature Based (figure 2), and Blended Curvature Based (figure 3) meshes on these two topologically identical parts:

Standard Mesh
Figure 2 - Standard Mesh
Curvature Based Mesh
Figure 3 - Curvature Based Mesh
Blended Curvature Based Mesh
Figure 4 - Blended Curvature Based Mesh

In each case, the mesh on the left part looks clean and orderly.  By contrast, the mesh on the right part looks distorted to varying degrees. Notably, the Blended Curvature Based mesh seems to generate the best quality elements out of all three meshes, but still struggles a bit with the right part.

Revealing the natural u-v curves of each surface tells the story of why the part on the right exhibits strange meshing behavior. To show these curves, use the Face Curves tool as shown in Figure 5.

Face Curves Tool
Figure 5 - Face Curves Tool
U-V curves on surfaces
Figure 6 - U-V Curves on Surfaces

The planar face on the right part was replaced with a custom freeform feature in this case. Deleting this face and patching back in a simple planar face fixes the problem here. Complex surfaces like this are a common cause of poor mesh quality and mesh failures so simplifying these surfaces can help to get a clean working model.