Accessing previous time step temperature in UDF
 

Hi everyone,

I'm trying to access the temperature from the previous time step on a face. I think I need to define a UDS but I'm not sure how. At present I have a line in a DEFINE_PROFILE UDF that says:

F_UDSI(f,t1,0)= F_T_M1(f,t1);

face_temp = F_UDSI(f,t1,0);

When I try to compile this I get the message "F_T_M1: undeclared variable"

Do I need to 1) #INCLUDE something more than udf.h. 2) Define the UDS somewhere else. 3) Do something else?

Thanks in advance for your help, Sam