Expression of 2ndary differential equation term
 

Dear everybody, In differential equation that I am willing to solve in Fluent 6.0.20, there is secondary differential term as follows;

A del^2 (T)

where A is constant, and T is temperature as fuction of distance.

All other expression for gradient were cmpleted to described in UDF, because they were 1st order of differential term, and remaining is above secondary differential term.

Could you let me know how I can describe this in UDF?

Thanks

J.W.Ryu