Mesh generation for wedge shaped blocks
 

I'm trying to modify a model for flow around a 180 degree bend by collapsing the corner blocks into a wedge shape, so that they have a 45 degree angle rather than a 90 degree angle. I'm having trouble with the generated mesh and was hoping someone could help. The link below shows the mesh.

www.hydrocalc2000.com/images/corner_mesh.jpg

As you can see from the image, the corners are successfully collapsed, but the mesh is collapsed as well, resulting in a cell distribution that isn't smooth. I'd like for the gridlines to follow the same straight lines as in the uncollapsed blocks. The cells on the collapsed edge would be wedges, in that case.

Any ideas on how to do this? Thanks