Using UDFs to create a contour plot
 

I am calculating exergy destruction for a combustion problem. I am new to UDF's and have a couple of doubts in applying UDFs to countour plots.

The mesh is 2D and for exergy calculation, i need temperatures and enthaplies at two different faces. In the contour plot, i notice you can specify UD scalars and memory only. UD scalars solves the transport scalar equation and hence is of no use to my porblem.

Since UDF cannot be chosen in contour plot, how do i apply the UDF calculation for each cell in my countour plot?