1. Toward Automatic Grid Generation Si Loi Leung

2. Mechanical Engineering Mentor: Dr. Nathan Prewitt University of Hawaii

3. Project Goals Write a program to generate shape structure graphs for any given boundaries Investigate how it could possibly be employed in automatic grid generation of any arbitrary boundaries

4. Outline How to create shape structure graphs Evaluation of the shape structure graphs A look at the medial axis

5. Grid Generation

6. Getting Complicated

7. Multi-Block Topology

8. Shape Structure Graphs Idea started from an article by Vitaly Ablavsky in the C/C++ Users Journal

9. Voronoi Diagram The Voronoi diagram of a collection of nodes is a partition of space into cells, where any point within a cell is closer to its respective node than to any others.

10. Voronoi in Action

11. Medial Axis The medial axis is the collection of center points of circles that touch the boundary at least twice.

12. Medial Axis in Action

14. Shape Structure Graph The shape structure graph is a meta-graph with respect to the medial axis and retains only the “interesting” vertices.

15. Shape Structure Graph

16. Easymesh/Showmesh Easymesh Bojan Niceno Generates two-dimensional unstructured meshes Showmesh is a graphical interface to show the results

17. Input 5 0: 0 0 5 1 1: 5 0 5 1 2: 5 2.5 5 2 3: 3.5 4 5 2 4: 0 4 5 1 # x y scale marker 5 0: 01 1 1: 12 2 2: 23 3 3: 34 4 4: 40 5 # a b marker

18. Output 3 0: 0 3 4 -1 -1 1 5 6 4 2.5000.25000 -1 1: 0 2 3 2 -1 0 4 2 1 2.4167 1.4167 -1 2: 3 1 2 -1 1 -1 3 1 0 1.7500 2.0000 -1 ------------------------------------------------------------------------ e: i, j, k, ei, ej, ek, si, sj, sk xV, yV sign

19. samples

23. Evaluation Shape structure graph? Medial axis graph?

24. TopMaker By David L. Rigby, QSS Group Technique to generate multi-block topologies using the medial axis

25. How to Divide

26. Creating the Multi-block Topology

27. Something Like This

28. Conclusion Work in progress What I learned –C/C++ –Linux –CFD Acknowledgement –Dr. Nathan Prewitt –PET staff –PET interns

29. Thank You