Thanks a lot for answering Sir/Madam Yes you are right, there is a very small curvature (Of radius 0.254 mm) in diverging part of nozzle compared to converging part of nozzle whose radius is (25.4 mm), But I don't know why while importing the geometry from solid works the small curvature is not shown in Ansys meshing.
I think, I should ignore that small curvature part and make it conical divergent section shape geometry without any curvature.
And I have another doubt in this is : As inflation was not working so I tried biasing option, it worked well despite of the small curvature part.
As you can see from the images that I only want boundary layer mesh around the "red marked " wall. (Blue marked is the line of truncation of nozzle) .
If I use inflation type or biasing type, it would automatically connect the domain outside if nozzle wall, which I don't want to happen

Are there any way to make boundary layer mesh only in the red marked region without linking this with entire domain of flow field and still getting structured mesh?
Are there any special ways to partition this geometry to get the desired results.
I cannot think of a way to stop the boundary layer mesh till wall and also have good structured mesh for interior flow domain.
I have tried the following grids with different partition line but this grids are not satisfactory as it links the boundary layer mesh with outside region of nozzle wall.

I am really struggling to get a structured mesh without BL mesh at nozzle exterior domain. (I want Type-5 type of BL mesh but without it being unstructured)
Please Help to solve this issue.