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Old   November 15, 2005, 22:15
Default Using UDF
  #1
Vidya Raja
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Hi,

I have an equation for unstaedy velocity. It is as follows:

Q = 0.35 + 0.35* sin(2*pi*0.5*t)

I wrote the following code in C to hook it to fluent:

unsteady.c UDF for specifying a transient velocity profile boundary condition ************************************************** ************************************************** ******/

#include "udf.h"

DEFINE_PROFILE(unsteady_velocity, thread, position) { face_t f; real t = CURRENT_TIME;

begin_f_loop(f, thread) { F_PROFILE(f, thread, position) = 0.35 + 0.35* sin(2.*pi*0.5*t);

} end_f_loop(f, thread) }

But when I hook it to fluent, it displays an error that says

parse error. What does this mean? Is there something wrong in my C code? How do I hook it to fluent?

Any help/ suggestions are highly appreciated.

Thanks, Vidya
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Old   November 17, 2005, 04:12
Default Re: Using UDF
  #2
RoM
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Dont interpret your udf from a directory which name has spaces like in "c:\my documents". This will give a line 1: parse error. Use M_PI instead of pi. Hook your udf in the bc panel for the velocity inlet.

Hope it helps, RoM
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Old   November 17, 2005, 10:55
Default Re: Using UDF
  #3
Vidya Raja
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Hi, Thanks for the help, but can I make the Desktop my working directory and then store the C file, and the case and data files on the desktop and work from there? If not, could you please tell me step- by- step how to do i

I use the compute in my lab and so temp files are deleted every day.

Sorry for bothering you.

Thanks, Vidya

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Old   November 17, 2005, 11:35
Default Re: Using UDF
  #4
RoM
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I have not found a way to work around this "no spaces in directory names allowed" feature (someone could call it a bug). You will have to interpret your udf from a directory with no spaces in name. Once the udf is interpreted, hooked and the case is running it doesnt matter if the file is deleted. Fluent will continue running and as long as you have a backup of your source file you should be fine.

RoM
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Old   November 17, 2005, 13:56
Default Re: Using UDF
  #5
Vidya Raja
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Thanks RoM.......... it worked. Thanks a lot, once again.

Vidya
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