[rezaaa2]

hi. i recently started to learn udf and want to use slip boundary condition(navier slip) in my project so i write a udf and compile it in fluent successfully. but when i initialization it encounter with this message:

Error: received a fatal signal (Segmentation fault)./Error Object: #f/
i found that this error occur when use velocity (C_U(cell,c_thread))or velocity gradient (C_U_G(cell,c_thread)[1]) in my udf and in other cases initialization is succesfull But I didn't understand where is problem ?

[pakk]

When you initialize, the data does not exist yet. If your UDF does a calculation with velocity, but velocity does not exist yet, you get this warning.

Solution : initialize without the UDF, and then activate it.

And I hope you know that first order velocity slip is implemented in Fluent, you don't need a UDF, just use low-pressure boundary slip...