The velocity field looks sensible, what shear (viscosity) are you predicting in Fluent? If you look at a 2d model you can use significantly more mesh.
I strongly advise switching to either Ansys Meshing (2d, found in Workbench) or Fluent Meshing (3d, use the standalone mode) rather than GAMBIT. Whilst I still like GAMBIT it's not been developed in over 15 years and it's not used in industry (much) any longer.
You are navigating away from the AIS Discovery experience