Rob
Ansys Employee

C_T ought to be fine, if that was causing a more general problem we'd know as it's about the most called value in Fluent UDFs. Programming question (I don't program much), how close to being an integer is the  RP_Get_Double(“var_aux”) value? I was always warned about setting 

value = other value 

as in computational terms there's aways room for variation at the 16th decimal place.