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Old   May 22, 2004, 07:02
Default User Defined Memory Problem
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Hi everbody,

I have a problem that may be a common problem for Fluent Users. I want to see pressure values of a wall by User Defined Memory at every iteration. The thing is that the pressure values are transfered to F_UDMI(t,f,0) in my UDF, but I can not see them in FLUENT. I mean, every values of F_UDMI(t,t,0) are zero in contour values windows in FLUENT. Here is the simple UDF that transfers pressure values to F_UDMI(t,f,0). Could you please tell me what is wrong with it?

#include "udf.h"


{ face_t f;

int ID = 8;

/* Zone ID for wall zone */

Thread *t = Lookup_Thread(domain, ID);

begin_f_loop(f, t)


F_UDMI(f,t,0) = F_P(f,t);

Message("pressure %e\n",F_UDMI(f,t,0));


end_f_loop(f, t)

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Old   May 24, 2004, 04:31
Default Re: User Defined Memory Problem
Andrew Garrard
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I have had exactly the same problem with the UDMI macro and the good people at the fluent USC couldn't help me much. I had to use a "dirty trick" to get around this one. If you assign the value of the F_UDMI to the adjcent cell you should then be able to see it in, say, a contour or XY plot with in fluent. If you need help doing this I can help you out with the source code, but you seem to know what you are doing, so I will leave it for the moment.

I hope this helps, happy coding.
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Old   May 25, 2004, 04:20
Default Re: User Defined Memory Problem
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I had the same problem too. Maybe it's a bug of FLUENT.


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Old   May 25, 2004, 21:39
Default Re: User Defined Memory Problem
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Have had a similiar problem, and the bug seams to go away (if the same bug) by first viewing the udm with contours (should be all zeros), then run your udf and then replot. It appears that viewing the udm initializies it for use (atleast thats one interpretation).
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