1. Semi-Automated Cleanup Tools

2. Semi-Automated Cleanup Tools
Clean up on models containing a large number of faces can be tedious.
Cleanup Tools can semi-automate this process using virtual and real operations.
Locate problem areas
Suggest repair method
Perform repair operation
The Cleanup tools are available from the Tools menu in GAMBIT.

3. Semi-Automated Cleanup Tools
Quickly identify, zoom in, highlight areas that cause connectivity and mesh quality problems.
Appropriate tools to fix problems are given.
Graphics color coding set to connectivity based coloring.
Graphics window pivot set to mouse.
Available Cleanup tools:
Clean up Short Edges
Clean up Holes
Clean up Cracks
Clean up Sharp Angles
Clean up Large Angles
Clean up Small Faces
Clean up Hard Edges
Clean up Fillets
Clean up Duplicate Geometry
Select cleanup Domain

4. Clean Up Short Edges Why clean up short edges?
Short edges can cause meshing difficulties such as large cell size change, highly skewed cells.
Tools to identify and highlight the problem spot
Cleanup domain
Select whole model or group
Maximum length: upper limit
Default: 10 × shortest edge in the Cleanup Domain
Items List: candidates for cleanup operation based on Cleanup domain and Maximum length
Current length: length of currently picked edge
Update: updates the Items list
Required when Maximum length is modified
Zoom
In/Out: quick auto zoom in on or from the picked items
Auto: automatically zooms in on selected item

5. Clean Up Short Edges Tools to identify and highlight the problem spot
Local: current item + all faces connected to it
Visible: make everything else invisible
Shade: shade the local objects
Options to Apply Cleanup Tool
Apply: applies appropriate fix to selected item
A/N: (Apply/Next) applies appropriate fix to selected item and automatically picks the next item in the list. The view is changed.
Auto: entire list is processes automatically (only works for the Method: Edge merge)
Ignore: removes selected item from list and selects next item
Restore: the list is restored

6. Clean Up Short Edges Methods to fix the problem spot
Vertex connect (least common)
Average location
Preserve location: first vertex
Preserve location: second vertex
Edge merge
Merge with (select edge)
Face merge
Faces to merge (select faces)
Edge merge pre-selected when at least one vertex has only one other connected edge.
Appropriate methods and applicable entities are often pre-selected, however users may edit them.

7. Clean Up Short Edges Before Cleanup, Face Contains a Short Edge
v_edge.5
edge.6
v_vertex.7
edge.2
v_edge.7
Before Cleanup, Face Contains a Short Edge
Virtual Face Created After Cleanup by Edge Merge

8. Clean Up Holes Why clean up holes?
Volumes must be “air-tight.” Holes in faces must be repaired in order to properly define volumes.
Holes in the model are internal edge loops that do not constitute external boundaries of a face (or faces)
Tools to identify and highlight the problem spot and Options to Apply Cleanup Tool
Similar to those for Cleanup Short edge
Method to fix the problem spot
Create Face from Wireframe
Real and Virtual options available

9. Clean Up Holes Before Cleanup, Face Contains a Hole
Virtual Face Created After Cleanup by Create Face from Wireframe

10. Clean Up Cracks Why clean up cracks in faces?
Cracks in faces cause meshing difficulties as well as disconnects which do not permit volume definition.
Tools to identify and highlight the problem spot
Maximum angle between edges defining the crack (default is 20)
Other tools similar to those for Cleanup Short edge
Options to Apply Cleanup Tool
Similar to those for Cleanup Short edge
Method to fix the problem spot
Connect edges
Tolerance: maximum distance between edges to be connected

11. Clean Up Cracks The edges that define the crack share one vertex
Virtual Face Created After Cleanup by Edge/Vertex Connect
Before Cleanup, Faces are Disconnected at Vertices with a Gap
edge.8
edge.4
vertex.5
face.2
face.1
v_edge.9
v_face.2
v_face.1
The edges that define the crack share two vertices
Virtual Face Created After Cleanup by Edge Connect
Before Cleanup, Face Contains a Crack
edge.8
edge.4
face.2
face.1
v_edge.9
v_face.2
v_face.1

12. Clean Up Sharp Angles Why clean up sharp angles?
Sharp angles cause meshing problems such as highly skewed cells and possible failure of meshing algorithms.
Tools to identify and highlight the problem spot
Maximum angle: default is 20
Other tools similar to those for Cleanup Short edge
Options to Apply Cleanup Tool
Similar to those for Cleanup Short edge
Methods to fix the problem spot determined by face-face angle
If face-face angle > 135: Merge faces
If face-face angle < 135: Chop one face and merge truncated face with neighboring face.
Distance: length of shortest boundary edge of truncated face θ
face–face angle: 180 – 
 is the angle between the normals of the two faces (shaded in grey)

13. Clean Up Sharp Angles (Without Chop)
Before Cleanup
3 faces (real or virtual)
Virtual
Virtual
After Cleanup
Merge with left face
After Cleanup
Merge with right face

14. Clean Up Sharp Angles (With Chop)
Truncated face
Merged face
Distance
Chop option
face - face angle < 135
Tri-primitive
Mesh: Cooper
1 of 8 Sharp Angles
Merge edges

15. Clean Up Large Angles Why clean up large angles?
Cleaning up large angles may help generate map mesh.
Tools to identify and highlight the problem spot
Maximum angle: default is 5 degrees
Other tools similar to those for Cleanup Short edge
Options to apply the Cleanup Tool
Similar to those for Cleanup Short edge
Method to fix the problem spot
Merge faces

16. Clean Up Large Angles 170° Before cleanup After cleanup
Two connected faces; face normals nearly parallel
After cleanup
One virtual face results from large angle cleanup operation

17. Clean Up Small Faces Why clean up small faces?
Small faces can cause meshing problems (similar to short edges)
Tools to identify and highlight the problem spot
Maximum area: default value is 100 times the area of the smallest face in the Cleanup domain
Items in the list contains all faces with areas less the maximum area
Other tools similar to those for Cleanup Short edge
Options to apply the Cleanup Tool
Similar to those for Cleanup Short edge
Methods to fix the problem spot:
Merge face
Collapse face
Candidate Faces to merge: all bounding faces with a face-face angle > 135 pre-picked

18. Clean Up Small Faces Before cleanup After cleanup
Small face causes meshing problems
After cleanup
One virtual face results from virtual merge operation

19. Clean Up Hard Edges Why clean up hard edges?
Cleaning up hard edges will simplify meshing by removing excess constraints
Hard edges are also known as dangling edges.
Creation occurs:
as a result of a face split when the split tool only partially intersects target face
from STL or mesh import
Tools to identify and highlight the problem spot and options to apply the cleanup tool
similar to those for Cleanup Short edge
Method to fix the problem spot
Remove all hard edges

20. Clean Up Hard Edges Before cleanup After cleanup
Face is split by a dangling (hard) edge
After cleanup
Virtual face with edge split

21. Clean Up Fillets Why clean up fillets?
Cleaning fillets will relieve meshing difficulties by simplifying faces. This can facilitate generating map/submap meshes.
Tools to identify and highlight the problem spot
Maximum angle: specifies the maximum deviation from 90o for outward-pointing normals computed at the boundaries of the fillet face.
Other tools similar to those for Cleanup Short edge
Options to apply the Cleanup Tool
Similar to those for Cleanup Short edge
Methods to fix the problem spot
Merge face
Collapse face
Candidate Faces
Faces to merge: all bounding faces with a face-face angle > 135 pre-picked
to collapse between: two opposite faces along the longest edges prepicked

22. After cleanup by face merge After cleanup by face collapse
Clean Up Fillets
Before cleanup
Fillet face can cause meshing difficulty
After cleanup by face merge
One virtual face results from virtual face merge
After cleanup by face collapse
Fillet face is divided; each part is merged with its adjoining face (suitable for volume map mesh)

23. Cleanup Duplicate Edges
Why clean up duplicate edges?
Duplicate geometry can cause discontinuities in the mesh and unintentional non-conformal interfaces.
Clean Up Duplicate Edges
Includes edges which are coincident in part (T-junction connect).

24. Cleanup Duplicate Faces
Two search options
Topology-based
All lower entities (edges or vertices) to be identical between the two faces.
Centroid-based
The centroids of the two faces should be within tolerance.
Less accurate, but helpful in detecting duplicate faces with different lower topology.
Method
Connect faces
Delete faces

25. Cleanup Duplicate Volumes
Method
Connect duplicate volumes
Delete duplicate volumes
Before cleanup
(Four volumes)
Duplicate Volumes
After cleanup
(Three volumes)

26. The Cleanup Domain is group2
Select Cleanup Domain
Specifies the domain to which the geometry cleanup operations apply.
Whole Model (default)
Predefined geometry group
The Cleanup Domain is group2

27. Where are the Problem Areas?
Cleanup Demo
Where are the Problem Areas?
Fillet
Short edge
Faces can be merged
Sliver face

28. Cleanup Steps
Import the .iges file using the default settings (Make tolerant).
Change color coding to connectivity.
Blue edges (2 connections) indicate connected geometry.
Apply Cleanup Tools (Virtual Geometry Created)
Short Edges
Holes
Large Angles
Fillets
Mesh using the Cooper Tool
Source faces