meshing a curved domain with mostly unidirectional flow
 

I have to mesh a solid somehow similar to a smoothly curved pipe. As flow is mainly unidirectional, I think it would be optimal if most cells have a face normal to the fluid speed (I know I could do it with thiner meshes without considering that). How would yo do it?

I was thinking in 2 approaches:
1) Fixing the former blockMesh with the direction normal to the "pipe" central section. So that at least angle between speed and normal to one face is not that important.
2) Is it possible to bend the former blockMesh prism?