Ansys meshing problem
 

Hi dear forumers,
I want to mesh a cubic cavity with a thin region in it. I defined nodes and edges then parted the cub in 8 sections to define surface and perform a mapped mesh. I did not use sketch method because it's not produce desired mapped mesh around thin region. problem arises when i import mesh in fluent and it assumes that section lines are wall.
how can i solve this problem?
Geometry pictures are attached.

Thanks in advance

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