# Meshing a Fillet

We often get asked about the best way to mesh a fillet. Let us look at one topology. The example here has 4 connectors - each with 11 grid points on them.

The easiest way to create a structured mesh on this fillet is to grab the four connectors and assemble a structured domain. However, the quality of the grid is very poor and running it through Grid, Solve does not improve it at all. If we look at the resultant domain with the Examine, Max Included Angle diagnostic, you can see that there is a very skewed cell right off the fillet.

It gets even worse if you want boundary layer resolution with a tighter spacing constraint towards the fillet. If you tighten the spacing constraints towards the fillet surface and run it through Grid, Solve, you will see that high values of Max Included Angle are pushed into the interior and you do not have great orthogonality or control.

Let us try meshing this fillet using a different topology that will allow us to have orthogonality off the surface and reduce the skewness of the cells in that region.

1. Select Pole connector from the toolbar by clicking on the drop-down arrow next to Create Curves

2. Place it at the center vertex (upper-right vertex) of the fillet.

3. OK
4. Create, Assemble Special, Domain
5. With Auto Complete checked and Auto Next Edge unchecked, select the connectors one at a time, going in a counter-clockwise direction.

6. We will now split away the pole.

7. Select the domain.
8. Edit, Split
9. In the Split Direction frame select J.
10. In the Advanced frame, enter 1 4 for IJK.
11. OK
12. Select the pole and delete it.

13. Select the remaining domain.
14. Edit, Split
15. In the Split Direction frame select I.
16. In the Advanced frame, enter 11 for IJK.

17. OK.
18. Select connectors AB and DA.

19. Dimension them to 11.
20. Select connectors AB, BC, CD and DA.
21. Click Assemble Domains.

22. Select connectors BE, CF and DG.
23. Dimension them to 11.
24. Change the spacing constraints shown in the figure below to 0.001.

25. Set the 3 spacing constraints shown in the figure below to 0.07 to ensure a smooth transition across the edge.

26. Select all the domains.
27. Grid, Solve
28. Go to the Edge Attributes tab
29. In the Boundary Conditions frame set the type to Floating.
30. In the Solve tab, enter 10 for the Iterations.
31. Run
32. OK

33. Select the domains.
34. Examine, Maximum Included Angle

You will notice that the quality of the mesh is much better. The Maximum Angle is much lower, using this approach as compared to the first approach.

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