Hi @hamish_234, @shenoy,
If I can add my input here, if what you’re going for is a “2D analysis” using the Empty2D boundary condition, I’d advise you not to gor for the extrusion mesh refinement but rather generate a 3D mesh, extrude it using ParaView+OpenFOAM and import it back in.
I go through the workflow in detail in this forum post:
Cheers
Igor