Did you setup "Fluent with meshing"? If it is, unfortunately i do not have enough information on it to help you. But if you set the mesh section differently, please open your mesh and view your skewness and orthogonal quality. When you select these sections, a graphic will appear below...
Another way is to use hybrid mesh or mixed element mesh to reduce grid skewness. Frankly speaking I don't know how you discretise NS eq. But I recommand you check term by term by solving basic problems. If you doubt viscous term, you can solve heat conduction eq. on very stretched tr...
I generated grid in GAMBIT, no error and no warning, no "highly skewness>0.97". But during iteration in FLUENT, there happened "tempe