blockMesh with geometric point merging fails on high-aspect ratio cells
Summary
Run a case with very high aspect ratio cells. Sometimes this can trigger the geometric point merging to merge points (because it thinks it is generating a wedge geometry)
Steps to reproduce
run
blockMesh
checkMeshand checkMesh reports 2 hexes. Now comment out the fastMerge and repeat. It will report two wedges.
This is a known problem of the geometric point merging - the topological fastMerge algorithm is also quicker to run.