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define wall functions (UDF) in Fluent 6.3

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Old   March 11, 2008, 13:32
Default define wall functions (UDF) in Fluent 6.3
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Alex
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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
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Old   March 24, 2008, 04:39
Default Re: define wall functions (UDF) in Fluent 6.3
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Dave S
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Before compiling the UDF in Fluent you need to start Fluent in a C++ DOS window.
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Old   March 24, 2008, 08:15
Default Re: define wall functions (UDF) in Fluent 6.3
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Alex
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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.

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Old   September 20, 2014, 12:37
Default meaning of DUPLUS AND D2PLUS
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Qureshi M Z I
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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
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Old   August 2, 2017, 00:01
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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.
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Old   August 2, 2017, 02:24
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Quote:
Originally Posted by yousefaz View Post
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
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Old   August 3, 2017, 07:45
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Quote:
Originally Posted by yousefaz View Post
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.

That's basically true.

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

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