Learning Forum

[aliborhan]

Hello,

 I am writing a UDF that includes a DEFINE_PROFILE macro for a transient simulation. My goal is to update the variable viscous resistance of a porous media during each time step. Since DEFINE_PROFILE macros are executed during every iteration within every time step, what can I do to ensure that the macro executes only once per time step? I tried using "first_iteration," but it didn't work within the DEFINE_PROFILE macro. Also, If I enter a large value for the UDF Profile Update Interval in the Run Calculation panel, I cannot be certain whether this value is greater than or less than the maximum number of iterations required for convergence.

Thank you in advance for your guidance!

[aliborhan]

Hello,

I am writing a UDF that includes a DEFINE_PROFILE macro for a transient simulation. My goal is to update the variable viscous resistance of a porous media during each time step. Since DEFINE_PROFILE macros are executed during every iteration within every time step, what can I do to ensure that the macro executes only once per time step? I tried using "first_iteration," but it didn't work within the DEFINE_PROFILE macro. Also, If I enter a large value for the UDF Profile Update Interval in the Run Calculation panel, I cannot be certain whether this value is greater than or less than the maximum number of iterations required for convergence.

Thank you in advance for your guidance!

[aliborhan]

Any thoughts on this?

Thanks!

[Luca B.]

Hi, DEFINE_PROFILE is executed at any iteration because you need to provide a boundary values to porosity. So it need to compute the corresponding value anytime.

How to do modify the viscous resistance? is it time dependent? 

Some ideas

• can you modify it only with Expression without an UDF. So you can calculate it without running the UDF?
• Another possibility, you can try. You can use a DEFINE_EXECUTE_AT_END  that is run only at the end of all time step. You can compute it the new viscous value, save it into a global variable and so make it accessible to the DEFINE_PROFILE macro.

Let me know if this suggestion are useful

 

Luca