Shadow wall in heat transfer problem
 

I have a small plate in a fluid zone . Fluid passes on either side of the plate and I want to carry out the convection due to difference in temperature between the fluid and the plate. I defined the plate as a wall. But when I'm importing the mesh into fluent it is creating a shadow face to this plate.

Now I'm no longer able to give the heat transfer coefficient for the wall and on top of it I have a shadow wall, whose properties I'm not sure what to give. I understand that Fluent is doing it for coupled heat transfer but my problem is not that. How to solve this??

Any help would be appreciated.
Thanks.