Is there a way to take an existing gmsh .msh file, and convert it to second-order elements? Specifically, I'm trying to go from 8-point hexahedra (hex8) to 20-point hexahedra (hex20). Ideally, I'd like a command-line solution. I tried this:
gmsh -o output.msh -format msh2 input.msh -order 2 -0
But it doesn't seem to work - I still get hex8 elements in the output. Is there a way to do this, or does the order need to be set when the mesh is first generated? I do need to maintain the gmsh version 2 format (unfortunately).