# Enosh, a structured grid generator (IV)

I have made significant improvement on the mesh export. The manual building up of OpenFOAM mesh now turns up really fast. I got a feeling that it could possibly beat even OpenFOAM’s native blockMesh generator. In my test of a $$3,200,000$$ mesh (for flow around a square cylinder). The building process took $$90.51$$s in total. Here are more details:

...... [1] Done assembling the points. ( 7.09000s)
...... [2] Done assembling all cells &amp; intnl cntrs. ( 40.62000s)
...... [3] Done treatment of cntrs and init o&amp;nbs. ( 27.74000s)
...... [4] Done assembling boundary cntrs and info. ( 9.77000s)
...... [5] Done assembling faces. ( 1.29000s)
...... [6] Done assembling owners on frontAndBack. ( 0.23000s)
...... [7] Done face orientation correction. ( 3.77000s)

This is a very exciting progress. As in the old days, I have to wait for 10 minutes for just a $$24,000$$ grid sized mesh. So the speed now scales roughly around $$O(N)$$, which is way better than $$O(N \log N)$$ or $$O(N^2)$$.

The renumber (e.g., using Cuthill–McKee algorithm) is needed, but it is not a big deal at this moment.

As for a smaller mesh, using the same blocks as before (8 blocks around the square), $$240,000$$ mesh size, it took:

...... [1] Done assembling the points. ( 0.53000s)
...... [2] Done assembling all cells &amp; intnl cntrs. ( 2.60000s)
...... [3] Done treatment of cntrs and init o&amp;nbs. ( 1.81000s)
...... [4] Done assembling boundary cntrs and info. ( 0.91000s)
...... [5] Done assembling faces. ( 0.10000s)
...... [6] Done assembling owners on frontAndBack. ( 0.01000s)
...... [7] Done face orientation correction. ( 0.28000s)