[Majid Zarif]

Hi Every body

I know that every UDF file should include
#include "udf.h"

but I saw other things like:

sg.h
or
prop.h

do any body know how can we understand how to use these headers?and also WHY we use them?

Thanks

[mprinkey]

Header files in C are essentially just another container for functions, variable declarations, and macros. They are not usually compiled by themselves into a standalone executable files. "Proper use" of header files are mostly to provide function prototypes for functions that are defined in a different .c file or exist in a pre-compiled library or executable, and maybe some supporting macros.

That is the case with udf.h. That header file (and it is distributed as source code with FLUENT ANSYS) has function prototypes and (many) macro definitions. F_C0, C_UDMI, etc are all defined as macros. All of the variables, function prototypes, and macros that UDFs generally need to access are defined in the udf.h file. But, there are other header files as well and those may contain function prototype/macro definitions that are not in udf.h but still may be useful. What those variables are and what use they are can only be sorted out by careful reading of the header files and trial-and-error testing, or by getting documentation or assistance from ANSYS.

[Majid Zarif]

So it's essential to know other header's usage in UDF ?
I mean I can always use udf.h instead of these headers?

[mprinkey]

Likely not. udf.h has most everything you should need to code UDFs.