UDF not working

daniel_ortega79 · July 29, 2012, 08:18

I am using a UDF for inlet velocity boundary(vx=2*y).when I interpret my UDF it doesn't show any error.But after selecting my UDF in B.C. when I want to initialize, it shows a constant velocity value. Is there anyone who knows what the problem is?

flotus1 · July 30, 2012, 03:03

Unless you show us the UDF you used, you will have to wait for a psychic with basic knowledge in UDF programming.
I can tell you that these people are quite rare

akm · July 30, 2012, 12:02

'Initialize' provides an initial solution over the entire domain. Through the Fluent GUI you can give only a single initial value for the entire domain. If you want the initial solution to be of the form Vx=2y, you will have to write an initialization macro (DEFINE_INIT).

However, im guessing you have written a udf for inlet B.C. (DEFINE_PROFILE), which will be used as the inlet velocity condition for obtaining the solution.

The initial solution is given to the solver as a starting point for the calculation, and should not affect the final solution (unless, of course, it is way off which will lead to a divergence).

akm · July 30, 2012, 12:05

Quote:

Originally Posted by flotus1

Unless you show us the UDF you used, you will have to wait for a psychic with basic knowledge in UDF programming.
I can tell you that these people are quite rare

@Alex.. yes, people like me are rare

hahaa

daniel_ortega79 · July 30, 2012, 16:37

thank you guys! yes I used (define_profile) for my inlet velocity. In fact the problem was due to the written code. I guess after this project I'll be more psychic than before

July 29, 2012, 08:18	UDF not working	#1
daniel_ortega79 New Member Daniel Ortega Join Date: Jul 2012 Posts: 3 Rep Power: 13	I am using a UDF for inlet velocity boundary(vx=2*y).when I interpret my UDF it doesn't show any error.But after selecting my UDF in B.C. when I want to initialize, it shows a constant velocity value. Is there anyone who knows what the problem is?

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July 30, 2012, 03:03		#2
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,399 Rep Power: 46	Unless you show us the UDF you used, you will have to wait for a psychic with basic knowledge in UDF programming. I can tell you that these people are quite rare

July 30, 2012, 12:02		#3
akm New Member Join Date: Jan 2010 Location: Netherlands Posts: 28 Rep Power: 16	'Initialize' provides an initial solution over the entire domain. Through the Fluent GUI you can give only a single initial value for the entire domain. If you want the initial solution to be of the form Vx=2y, you will have to write an initialization macro (DEFINE_INIT). However, im guessing you have written a udf for inlet B.C. (DEFINE_PROFILE), which will be used as the inlet velocity condition for obtaining the solution. The initial solution is given to the solver as a starting point for the calculation, and should not affect the final solution (unless, of course, it is way off which will lead to a divergence).

July 30, 2012, 16:37		#5
daniel_ortega79 New Member Daniel Ortega Join Date: Jul 2012 Posts: 3 Rep Power: 13	thank you guys! yes I used (define_profile) for my inlet velocity. In fact the problem was due to the written code. I guess after this project I'll be more psychic than before