A problem with meshing a duct geometry
 

I just faced a problem with my fluid domain. As you see in the picture, there is a triangular area in the geometry which ansys mesher wont detect it's edges and twists the elements around that edge. I couldn't understand what is the problem with that edge!!
I'm also attaching the picture of my fluid domain, Does anyone have a general idea how can I have hex elements with infilation layers for this geometry?
Thanks a lot for your attention