define wall functions (UDF) in Fluent 6.3
 

Hello all,

I have been trying the example of DEFINE_WALL_FUNCTIONS in the Fluent 6.3 UDF manual (paragraph 2.3.23), but it doesn't seem to compile in Fluent. What I get in the log report is the following:

udf_names.c:8: error: 'user_log_law' undeclared here (not in a function)

udf_names.c:8: error: 'UDF_TYPE_WALL_FUNCTIONS' undeclared here (not in a function)

Could it be the case that I need to give some additional details in the UDF script?

Alex

Re: define wall functions (UDF) in Fluent 6.3
 

Before compiling the UDF in Fluent you need to start Fluent in a C++ DOS window.

Re: define wall functions (UDF) in Fluent 6.3
 

Thanks for your reply,

I figured out what was the problem. I was using the udf.h file from the previous version (6.2) so I updated the new one.

Alex.

meaning of DUPLUS AND D2PLUS
 

hi,

anybody know the meaning of DUPLUS and D2PLUS. these terms are used in UDF wall function example and also why the equation of both terms are different,

thanks
zahid

When defining a wall function UDF in Fluent, the user is required to specify equations for the dimensionless velocities U* and its derivatives with respect to dimensionless distance away from the wall (y* or y+).

Hence, DUPLUS is the first derivative: dU*/dy+ and D2UPLUS is the second derivative d2U*/d(y+)2.

thanks yousefaz

That's basically true.

You might want to give a look at this for more details:

https://www.politesi.polimi.it/bitst...Monticelli.pdf