How to access surrounding variables?
 

I want to define heat flux through a boundary. q=h(Tw-Tf)
I can access the wall temperature by subroutine on the wall. But how can I get access to the wall temperature and the surrounding fluid temperature at the same subroutine?
Since the User_get_var can only get varible of the current domain.
How can I get the surrounding domain and save that in the memory?
Also, I need to get the centroid axis of each surronding mesh unit.

Those above can be easily fullfilled by UDF in Fluent. But it seems much more difficult for CFX to do it.

I am in a urgent to do the simulation. Thanks a lot for kind help!