Why am I getting an incorrect field solution for this air coil in Workbench 9.0?
I created a large enclosure around the coil.
The mesh of the large enclosure becomes more coarse as it moves inward from
the surface. The line body representing the coil is entirely in a single element. It is
possible to define two enclosures, a small one just barely enclosing the coil and a
large one. This gives the expected maximum field results for your air coil (3 Tesla.)