Somome one can help me with theory or how can i create meshin on 3d? thanks

If you need 3D mesh for Fluent, I would recommend starting from Gambit tutorials. regards

Yes but here not tell us what kind ok mesh we need to use

for better result, very small interval is good choice with mapped mesh type

but when 3D has many small arc(complicated geometry) it will challange us, sometimes fail..

so meshing in in small edge will help then mesh volume completly