Mesh Quality

1
Mesh Quality Improvement

• Quality Metrics
• Mesh Smoothing

2
Exercise 10a Surface and Volume Smoothing

• import acis cadsmooth_2.sat
• Set volume 1 interval size to 5
• Set volume 1 scheme to sweep with source surf 7
  target surf 4
• Set volume 1 sweep smooth linear
• mesh volume 1

3
Mesh Quality

• Error always printed if inverted elements
  generated.
• Warning sometimes printed if poor quality element
  generated
• Good idea to check quality explicitly before
  export!

4
Mesh Quality Metrics

• Inverted Elements shape or scaled jacobian
• Shape shape or condition number
• Size size (element / total area or volume)
• Aspect Ratio aspect ratio
• Quality metric default shape

Quality Describe tri tet quad hex
5
Mesh Quality Panel
Go to MeshingVolumeQuality
--Or--
Go to MeshingSurfaceQuality
Select entity to check
Set quality metric here
Select output options
6
Exercise 10b Check Mesh Quality
1) Go to MeshingVolumeQuality
2) Select volume 1
3) Select the Draw tab
4) Check the Draw box
5) Click the Mesh radio button
6) Hit Apply
7
Exercise 10b Check Mesh Quality
8
Surface Smooth Schemes

• Winslow
• fast and high quality, try first
• Laplacian, centroid area pull
• fast, poor near concave features
• Untangle
• remove stubborn inverted elements
• Condition number
• improve stubborn low-quality elements
• inverted will automatically call untangle at start

9
Volume Smooth Schemes

• Laplacian
• fast, poor quality near concave features
• Equipotential
• medium fast and medium quality
• Untangle
• remove stubborn inverted elements
• Condition number
• improve stubborn low-quality elements
• inverted will automatically call untangle at start

10
Untangling
Smooth scheme untangle inverted -gt just barely
positive
Before
After
11
Smoothing
Before
After
12
Smoothing Panels
Go to MeshingVolumeSmooth
--Or--
Go to MeshingSurfaceSmooth
Select entity to smooth
Set smooth scheme here
Adjust defaults if needed
Smooth the entity
13
Exercise 10c Surface and Volume Smoothing

• Smooth surface 4 with Laplacian fixed, check
  quality - its bad
• Smooth surface 4 with Winslow fixed, check
  quality
• Smooth volume 1, check quality

14
Sweep Smoothing

• vol 1 sweep smooth AUTOcopylinearresidualwins
  low
• Auto
• fast and robust quality
• switches between linear and other smoothing,
  layer by layer
• linear for fast linear transform
• e.g., translate, rotate, scale
• copy to preserve source features, bias
• residual faster than Winslow and copy, better
  quality that linear
• Winslow for robust quality
• wavy source or target, wildly varying
  cross-sections, or poor quality side meshes

15
Exercise 11 Sweep Smooth

• import acis cadsmooth_2.sat
• Set volume 1 scheme to sweep with source surf 7
  target surf 4
• Set volume 1 sweep smooth winslow
• Set volume 1 interval size to 5
• mesh volume 1
• Check quality volume 1