export to su2 writes unused points
SU2 expects that all points (as defined in the section NPOIN=) are used to define mesh elements (as defined in the section NELEM=). If unused points are found, su2 will not accept the mesh. Currently the gmsh export to su2 needs some additional postprocessing before it can work with su2 when unused points are defined (like for instance when defining circles or rotational extrusion).