Cell neighbor lists

[markmbaum]

It would be useful to provide lists of neighbor cells for each cell in a mesh. I don't know of the most efficient way to do it, but most applications require neighborhoods.

[nschloe]

That'd rather be the job of a mesh processing lib like meshplex.

Edit: That being said, I don't think that cell neighbors is an efficient data structure. For triangles, you'd have to keep around four arrays: One for the triangles without neighbors, one for the triangles with one neighbor, etc. Plus a list that maps the triangle indices into each of the lists. Granted, most triangles will "probably" have three neighbors, but still.

In many applications, you can probably get away with just facet data information (basically a list of neighborhood info, like [(1, 2), (1, 3), (2, 5), (2, 7), ...]).

[nschloe]

Right. Same question though!

[markmbaum]

Would be nice to get model-ready meshes for simple domains like that without having to touch a fully featured mesh generator, but just a suggestion, of course!

[markmbaum]

Right. Same question though!

Well, you need to compute various relations between cells and their neighbors, so you need to know what the neighborhoods are.

[markmbaum]

You're right that facets are enough, though

[nschloe]

For FVM you don't need neighbor info. It's sufficient to consider cells individually. The complicated thing is to split up each cell into the parts that "belong" the each of its nodes. Some years ago I wrote meshplex and pyfvm to to just that.