[ICEM] What caused these low quality elements in the structured mesh?
 

Hello!
I'm modelling heat transfer between inner and outer turbine casings. I used ICEM to generate the structured mesh and have some problems at the exhaust pipe of the outer casing. It is a small cylinder shape on the top of the outer casing. When I checked the mesh quality, the quality of some cells around the corners are really low. I've attached the geometry, and the blocking of the casing, the number of nodes I've set and the zoom in view of the elements which have serious problems.

Does anyone know what my cause the problem and how may I solve it?

Below are links of the images. Many thanks in advance!

https://drive.google.com/file/d/0B4r...ew?usp=sharing

https://drive.google.com/file/d/0B4r...ew?usp=sharing

https://drive.google.com/file/d/0B4r...ew?usp=sharing

https://drive.google.com/file/d/0B4r...ew?usp=sharing