Boundary Element Parent Cell Search
 

Hello,

I have a situation where I receive an incomplete CGNS file that does not specify the parent cell for boundary faces. The search method I have right now is extremely slow and I'm looking for some way to accelerate the process. So the question is, for an unstructured mesh, does anybody know a fast algorithm for find the parent cells for a given boundary face?

You do not say what you are doing now but the following is straightforward to implement:
- separate out the 3D elements with boundary faces (no connectivity) into a separate list
- insert these boundary 3D elements into an octree
- search only the few relevant cell/s in the octree to find a match for your boundary elements

There is plenty of code for octrees (and other types of trees) for Fortran/C/C++ on the web.