Hello, everyone. Now I want to define the source of user defined scalar which includes the effect of the scalar itself. In numerical method, I know that we could use the value from last time step to calculate the value of this time step and iterate. Is it possible for me to write a UDF to carry out this process in FLUENT of UDS? If you could give me a similar example, I would be appreciated it very much. Thanks in advance.

Hi summer-

Yes, it can be done using UDF. I suggest you read the UDF manual on the chapter "User-Defined Scalar Transport Modeling". You'll also need to read sections for DEFINE_SOURCE and DEFINE_UDS_UNSTEADY macros.

Thanks! I am looking at these documents. Now, I would like to get the value of void fraction in the previous step, but I could not find the macros for it. Is there any other way I could get it? Thanks very much.